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    PIR to Arduino and LEDs #2

    Hello Electro Tech Online Forum,

    Its been a while since have been on the forum.
    Had to wait for the PCBs to get from Minnesota to Texas.
    Then I had a couple honey-do's but I am finally back
    in the saddle.

    To provide context here is the system complete.
    It has been named PODACAL as an acronym of
    PIR Optocoupler Arduino DMOS Array LED.

    PODACAL_12v_complete_201019.jpg

    The excellent schematic by eTech separates
    the system into three subsystems or modules:
    The LED Module
    The Sensor Module
    and the
    Main Module.

    One channel of the system complete has been
    tested with the Arduino has been breadboard
    tested and works as designed.

    The LED Module PCB was tested
    and works as designed.

    Having a little trouble with the Sensor
    Module. Here's the PCB
    Sensor_Mod_201007.jpg


    and drawing with components shown on
    the board that is a little easier to read.

    Sensor_Mod_201007_w_components.jpg

    These are the test performed

    Test 1.
    DC voltage at the power source fixed block terminal
    DC ground power source fixed block terminal
    Expected result: 12 volts
    Actual result: 12.4 volts

    Test 2.
    DC voltage on the PIR out side of R15
    DC ground power source fixed block terminal
    Expected result before movement near PIR: 0 volts
    Actual result before movement near PIR: 0 volts
    Expected result after movement near PIR: 3.3 volts
    Actual result after movement near PIR: 2.0 volts


    Test 3.
    DC voltage at fixed block terminal marked +PIR Out
    DC ground at fixed block terminal marked +PIR Rtn
    Expected result before movement near PIR: 0 volts
    Actual result before movement near PIR: -.76 volts
    Expected result after movement near PIR: 12 volts
    Actual result after movement near PIR: -.01 volts

    Test 4.
    DC voltage at fixed block terminal marked +PIR Out
    DC ground at power source fixed block terminal
    Expected result before movement near PIR: 0 volts
    Actual result before movement near PIR: 0 volts
    Expected result after movement near PIR: 0 volts
    Actual result after movement near PIR: 0 volts

    So the two highest possibilities are the tests
    3 and 4 are incorrect. Or the implementation
    of the PCB from the schematic has some fallacy.

    Thanks.

    Allen in Dallas
     
    Last edited:

    Pommie

    Well-Known Member
    Most Helpful Member
    With four 430R resistors in series with the opto LED you will only get 6mA of current - the datasheet suggests 50mA. However, as I said on your previous thread, I don't understand why this is so complicated. Why not connect the PIR output direct to the Arduino input?

    Mike.
     

    eTech

    Active Member
    With four 430R resistors in series with the opto LED you will only get 6mA of current - the datasheet suggests 50mA. However, as I said on your previous thread, I don't understand why this is so complicated. Why not connect the PIR output direct to the Arduino input?

    Mike.
    Hi mike

    As I explained in a previous post, for two reasons, 1)Because the PIR does not output enough voltage to be reliably sensed by the arduino input, and, 2) because we needed some transient protection for the long wires against carpets, rugs, whatever.
    The opto's aren't a big a deal. The OP is new to this stuff.

    eT
     

    eTech

    Active Member
    Hi Alan,

    Looks like R16 is connected incorrectly. One end should connect to PIR_out and the other end to +power supply terminal. Disconnect the end that connects to -power supply and connect it to +power supply.
     

    Pommie

    Well-Known Member
    Most Helpful Member
    The OP is new to this stuff.
    That was kinda my point. Why is there 4 resistors when 1 will do? Why is the LED current only 6mA? Why not use a 3.3V Arduino?

    It just seems like overkill but the OP seems happy, so carry on.

    Mike.
     

    gophert

    Well-Known Member
    Most Helpful Member
    Get rid of all the resistors and the opto.

    the PIR already has a base resistor for the 2n3904. If you connect that to the Arduino's 5v source to the 2n3904, all will be good to convert the PIR 3.3v output to a 5v signal. Since you have a bunch of channels, use 10k to 15k resistors from the 5v arduino supply to each 2n3904 collector.

    if you are good at soldering, there is room on the PIR to put an SMD transistor (the 0 ohm jumper on the PIR must be removed)

    cheers.


    48C5AA69-8044-4E0A-8A96-8050BBF73BF9.jpeg
     
    Hello Pommie, eTech and gophert,

    The input from Pommie and gophert is appreciated and has been studied.
    But the system has been taken so far down the road, through breadboard
    and PCBs the plan is to the stay the course with the schematic dated 200812
    rather than redesign the system at this stage.

    Two questions please
    '
    1. I eTech's rely, post #3 :
    'The opto's aren't a big a deal. The OP is new to this stuff.'
    The 'OP' is the other person?

    2. Just to be clear the drawing of the Sensor module PCB
    is refactored herewith.
    Sensor_Mod_201020_w_components.jpg
    This correctly reflects the direction given in post #4, right?

    Based on feedback will order new sensor PCBS, but looks like
    I could, first, take an Exacto blade and cut the trace between R16
    and the ground fixed block terminal. And second, run a jumper
    wire between R16 and the plus 12v post of the terminal block.
    Still going to order new PCBs but this rig would be a way
    of testing the refactor.

    One last thing, when the sensor board is refactored, the way
    POCADAL 200812 (post #1) is read, the output from R18 and
    R16 at the posts marked 'PIR Rtn' and '+PIR Out' should be
    about twelve volts, right? That is, when the Sensor board is
    supplied 12 volts then when the PIR is activated, with ground
    probe of the DMM connected to the 'PIR Rtn' post and the plus
    DC voltage probe connected to the '+PIR Out' post the reading
    should be about 12 volts.

    Thanks.

    Allen in Dallas
     

    eTech

    Active Member
    But the system has been taken so far down the road, through breadboard
    and PCBs the plan is to the stay the course with the schematic dated 200812
    rather than redesign the system at this stage.
    The design will be ok as is. We already know it will work as designed.

    1. I eTech's rely, post #3 :

    The 'OP' is the other person?
    OP = Original Poster (person).
    Some forums use TS = Thread Starter

    2. Just to be clear the drawing of the Sensor module PCB
    is refactored herewith.
    View attachment 127569
    This correctly reflects the direction given in post #4, right?
    Looks correct.

    Based on feedback will order new sensor PCBS, but looks like
    I could, first, take an Exacto blade and cut the trace between R16
    and the ground fixed block terminal. And second, run a jumper
    wire between R16 and the plus 12v post of the terminal block.
    Still going to order new PCBs but this rig would be a way
    of testing the refactor.
    Yes. that would be a good way to test.

    One last thing, when the sensor board is refactored, the way
    POCADAL 200812 (post #1) is read, the output from R18 and
    R16 at the posts marked 'PIR Rtn' and '+PIR Out' should be
    about twelve volts, right? That is, when the Sensor board is
    supplied 12 volts then when the PIR is activated, with ground
    probe of the DMM connected to the 'PIR Rtn' post and the plus
    DC voltage probe connected to the '+PIR Out' post the reading
    should be about 12 volts.

    Thanks.

    Allen in Dallas
    When no motion is detected, there should be less than 0.7 volts at the base of Q1. This keeps Q1 off.
    With Q1 off, there should be about 12.0v at the collector of Q1.

    When motion is detected, there should be about 2.0 volts at the base of Q1. This turns Q1 on.
    With Q1 on, there should be less than 0.7v at the collector of Q1.

    After the board is reworked and with 12 vdc power applied to sensor module:
    + PIR out terminal should read a constant 12 vdc.
    ( + probe to +PIR out, ground probe to -Pwr terminal on the sensor module)
    (12 vdc is present at both ends of R16)

    To test the sensor module:

    1. Connect a temporary jumper from +PIR out to PIR Rtn.
    2. Connect the DMM +probe to either the temporary jumper, or the +PIR out terminal. (make sure the jumper is in place)
    3. Connect the DMM ground probe to -PWR
    4. Connect 12 vdc power to the +PWR and -PWR terminals.
    5. The DMM should read about 12 vdc with no motion detected (doesn't need to be exact).
    6. Cause motion to be detected by the PIR (a wave of a hand over the PIR).
    7. The DMM should read less than 0.7 vdc with motion detected (doesn't need to be exact).

    eT
     
    Last edited:
    Hello eTech and the ETO forum,

    Won't get to test the refactored Sensor module
    until Saturday or Sunday because I have this deal
    with mortgage company: I work, get paid
    and pay them whole bunch of after-tax dollars
    and they let me live in my house.

    Meanwhile have been studying the schematic of the
    Sensor module and comparing it to the excellent
    seven-step test plan offered in post #8.
    PODACAL_12v_Sensor_mod_schematic_201023.jpg
    To paraphrase the test plan: the the outputs from the Sensor
    module are connected, the 12v volt power is applied
    and at the outward side of R16 the DMM should read
    12v (+ or - ) with no signal from the PIR (no motion)
    and .7 v (+ or -) when a signal is sent from the PIR.

    But looking at the schematic it seems to say at
    PIR1 rtn
    H=12.0=Motion
    L=0.0v= No Motion
    (blue font)

    So this seems to contradict the test plan.
    The test plan says 'no motion 12v' while
    the callout on the schematic '12.0=Motion'.

    Was the PIR1 rtn callout put on the schematic before it was
    changed from 5volt to 12 volt in post #11 of the thread
    marked 'PIR to Arduino to Transistor and LEDs'
    in mid July?

    Or am I misreading the schematic?

    Thanks.

    Allen in Dallas
     

    eTech

    Active Member
    But looking at the schematic it seems to say at
    PIR1 rtn
    H=12.0=Motion
    L=0.0v= No Motion
    (blue font)

    So this seems to contradict the test plan.
    The test plan says 'no motion 12v' while
    the callout on the schematic '12.0=Motion'.
    Hi

    The "blue font" at the output of the sensor module is incorrect. However, the test plan does need a minor correction
    The blue font at the sensor output should read:

    H=12.0=No Motion
    L=10.0v=Motion

    Meaning:
    There should be 12.0 vdc when no motion.
    There should be <10.0 vdc when motion detected.

    The test plan should be updated as follows.

    7. The DMM should read less than <7.0 vdc with motion detected (doesn't need to be exact).

    The sensor module output voltage will be different for the module test because we are using a jumper between the +PIR_out and PIR_rtn.
     
    Last edited:
    Hello eTech and the ETO forum,

    Finally got the chores done and got back to the bench.

    Refactored the Sensor PCB, loaded it up and performed the
    seven step test.

    The outcome from the no-motion test is as expected, 12.39 volts.
    Sensor_7_53_600_800.JPG
    However the read out from the nine seconds after motion is detected is 7.53, not .7 (plus or minus) that was expected.

    It was conjectured that some mistake had been made. A second board was loaded.
    Using a one sixteenth inch drill bit with a hand tool the R16 is disconnected from the voltage plus terminal.
    Sensor_hack_201025_600_800.JPG

    It was checked to make sure there was no continuity between R16 and ground.
    Found the lead from R16 could be insulated and connected to the V+ power fixed terminal.
    Sensor_back_201025_2_600_800.JPG

    This is how the board looks with with all parts loaded except the PIR and the capacitor so the PCB can be seen before the cap and the PIR obstruct the view.

    Sensor_wo_cap_201025_600_800.JPG

    Performed the test on the second board:

    Ground probe at power source ground and +voltage probe connected to the
    jumper between PIR Rtn and +PIR Out, before movement at PR.
    Expected result: 12 volts
    Actual result: 12.39 volts


    Ground probe at power source ground and +voltage probe connected to the
    jumper between PIR Rtn and +PIR Out, after movement at PR.
    Expected result: .7 volts (+ or-)
    Actual result: 7.83 volts

    It seems like the difference between .7 and 7.53 or 7.83 is not within tolerances.

    So guess maybe the same mistake was made on both boards. Have checked to make sure that the
    PCB shown in the photo above marked 'OCADAL (PirOptoCouplerArduinoDr' matches the
    drawing of the board titled 'Sensor 201020' shown in post #7.

    Thanks.

    Allen in Dallas
     

    gophert

    Well-Known Member
    Most Helpful Member
    I don't understand how you expect 0.7V with the voltage divider network you set up. I showed you how to get to get your low active in post 6.

    here is the simple ohms law review of your design (voltages in red).

    15381DAD-E8E0-4628-82C5-D577DCDBBBA2.jpeg
     
    Hello gophert, eTech and the ETO forum,

    Ok I got a little confused. Post #8 indicated
    7. The DMM should read less than 0.7 vdc with motion detected (doesn't need to be exact).
    But then in post # 10 step seven was updated

    7. The DMM should read less than <7.0 vdc with motion detected (doesn't need to be exact).
    So the 7.53 reading means the Sensor modules are performing as designed.
    Staircase_Main_Board_201024_w_comps.jpg
    So the Sensor modules go into the main board at the fixed terminal blocks
    S1 thru S8

    The fixed terminal blocks LM1 thru LM7 go out to the ground sides of the
    LED modules.

    Need to think thru the logic used to design the main board a couple of months
    ago. Its getting late and having a hard time figuring out the rationale.

    Thanks.
    '
    Allen in Dallas
     

    Pommie

    Well-Known Member
    Most Helpful Member
    It looks like your supply is ~12.5V and you have a voltage divider to give you half the voltage from 12.5 to the collector of the transistor. As you're getting 5V across the top resistor (12.5-7.5) then you should have the same across the bottom one which suggests you have 2.5V across the transistor. Can you measure across the transistor?

    Mike.
     

    eTech

    Active Member
    Before I comment, be aware that when I state measurements, I'm working on a bench with a breadboarded circuit. The bench power supply is initially adjusted to 12.0 vdc without load, then re-adjusted for 12.0 vdc after connecting the load.

    You should do the same before making measurements.

    Hello eTech and the ETO forum,

    Finally got the chores done and got back to the bench.

    Refactored the Sensor PCB, loaded it up and performed the
    seven step test.

    The outcome from the no-motion test is as expected, 12.39 volts.
    View attachment 127654
    However the read out from the nine seconds after motion is detected is 7.53, not .7 (plus or minus) that was expected.
    7.53 volts is a little high but OK. There will be tolerance differences between your parts, test bench, and mine.
    Even the solder joint quality can make a difference. Poor quality joints can raise resistances and drop less voltage than expected.

    It was conjectured that some mistake had been made. A second board was loaded.
    Using a one sixteenth inch drill bit with a hand tool the R16 is disconnected from the voltage plus terminal.
    I think you mean "minus" terminal.

    View attachment 127655

    It was checked to make sure there was no continuity between R16 and ground.
    Found the lead from R16 could be insulated and connected to the V+ power fixed terminal.
    View attachment 127656

    This is how the board looks with with all parts loaded except the PIR and the capacitor so the PCB can be seen before the cap and the PIR obstruct the view.

    View attachment 127657

    Performed the test on the second board:

    Ground probe at power source ground and +voltage probe connected to the
    jumper between PIR Rtn and +PIR Out, before movement at PR.
    Expected result: 12 volts
    Actual result: 12.39 volts
    12.39 ok.

    Ground probe at power source ground and +voltage probe connected to the
    jumper between PIR Rtn and +PIR Out, after movement at PR.
    Expected result: .7 volts (+ or-)
    Actual result: 7.83 volts

    It seems like the difference between .7 and 7.53 or 7.83 is not within tolerances.

    So guess maybe the same mistake was made on both boards. Have checked to make sure that the
    PCB shown in the photo above marked 'OCADAL (PirOptoCouplerArduinoDr' matches the
    drawing of the board titled 'Sensor 201020' shown in post #7.
    No mistake. 7.83 volts is a little high but OK. That is close enough to the expected results of <7.0v

    My "sensor module" test readings:

    PWR: 12.0 vdc

    Volts at jumper:
    no motion=12.0 vdc
    motion detected=6.01 vdc

    Volts at Q1 Collector to gnd:
    no motion=12.0 vdc
    motion detected=68.0 mvdc
     
    Last edited:

    eTech

    Active Member
    Here are my bench measurements for the sensor module with jumper in place. Power supply is set to 12.0 vdc

    1603677982745.png
     
    Last edited:
    Hello gophert, eTech and the ETO forum,

    The Arduino Shield Main Board for the Staircase project
    was designed over a month ago. Last night when the
    Sensor module was tested positive a look at the at
    the Main board/shield was taken to begin connecting the Sensor modules
    and LED modules for staircase mockup.

    There were several things that did not make any sense
    on the PCB marked 'POCADAL Main Board 201024' in
    Staircase_Main_Board_201024_b.jpg
    post # 13 above and copied here. Among other things what is the function
    of the terminal blocks (six positions at top
    and three positions beneath) to the left of
    pads numbered vertically from 2 to 10?

    Today, Monday I had the day off from work so
    'POCADAL Main Board 201024' shown in post # 13
    was studied to make sure it was an implementation
    of the schematic dated 201012 in post #1 of this thread.
    This is a sort of a schematic/PCB drawing used to
    analyze the schematic deployment to a PCB.
    PODACAL_12v_Arduino_Shield_Main_Board_201026.jpg

    Today it was realized that in late Aug in the thread
    called PIR to Arduino to Transistor and LEDs
    at post #48 eTech suggested that the
    Link to PIR to Arduino to Transistor and LEDs post #48
    opto-couplers be moved from the Sensor modules
    to the Shield/Main board because the function
    of the opto coupler is to reduce EMI in
    the long runs between the Sensors and the
    Shield. So the FTBs (fixed terminal blocks)
    at the headers going thru pads 2 to 10
    to the Uno were obviated by the FTBs
    marked S1-S8 near the 430 ohm resistors.
    That is, the FTBs on the Sensors modules
    were moved to the Shield but I forgot
    to remove the FTBs designed to receive
    the wires from the sensors.

    Other 'Oh shoots' and 'I-don't-
    believe-I made -such-dumb-ass -
    mistake's' were found and refactored.

    So if you have a chance, please
    check out the the drawing marked
    POCADAL Arudino Shield and Main Board
    201026 posted herewith above.

    Especially concerned about the connection
    of the opto-coupler collector connection to the Arduino
    5v supply via R8 22k resistor.

    In building a shield for the Arduino
    one of the toughest parts was getting
    the pads in the PCB to line up with the pin
    headers on the Arduino. It took
    a set of digital calipers and a lot of time
    but the alignment was achieved. What
    was missed was the top of the USB
    port and the power barrel jack is
    higher than the pin headers. That is why
    in the PCB drawing in post #13
    ('POCADAL Main Board 201024') there
    are two leave-outs at the bottom of the board
    between S4 and S5 and between S6 and S7.

    The plan is to based on the always excellent
    feedback from the ETO forum, redesign 'POCADAL Main Board 201024'
    this Saturday and re-order a new board.

    Thanks.

    Allen in Dallas
     
    Last edited:

    eTech

    Active Member
    Hello gophert, eTech and the ETO forum,

    The Arduino Shield Main Board for the Staircase project
    was designed over a month ago. Last night when the
    Sensor module was tested positive a look at the at
    the Main board/shield was taken to begin connecting the Sensor modules
    and LED modules for staircase mockup.

    There were several things that did not make any sense
    on the PCB marked 'POCADAL Main Board 201024' in
    View attachment 127671
    post # 13 above and copied here. Among other things what is the function
    of the terminal blocks (six positions at top
    and three positions beneath) to the left of
    pads numbered vertically from 2 to 10?

    Today, Monday I had the day off from work so
    'POCADAL Main Board 201024' shown in post # 13
    was studied to make sure it was an implementation
    of the schematic dated 201012 in post #1 of this thread.
    This is a sort of a schematic/PCB drawing used to
    analyze the schematic deployment to a PCB.
    View attachment 127670

    Today it was realized that in late Aug in the thread
    called PIR to Arduino to Transistor and LEDs
    at post #48 eTech suggested that the
    Link to PIR to Arduino to Transistor and LEDs post #48
    opto-couplers be moved from the Sensor modules
    to the Shield/Main board because the function
    of the opto coupler is to reduce EMI in
    the long runs between the Sensors and the
    Shield. So the FTBs (fixed terminal blocks)
    at the headers going thru pads 2 to 10
    to the Uno were obviated by the FTBs
    marked S1-S8 near the 430 ohm resistors.
    That is, the FTBs on the Sensors modules
    were moved to the Shield but I forgot
    to remove the FTBs designed to receive
    the wires from the sensors.

    Other 'Oh shoots' and 'I-don't-
    believe-I made -such-dumb-ass -
    mistake's' were found and refactored.

    So if you have a chance, please
    check out the the drawing marked
    POCADAL Arudino Shield and Main Board
    201026 posted herewith above.

    Especially concerned about the connection
    of the opto-coupler collector connection to the Arduino
    5v supply via R8 22k resistor.

    In building a shield for the Arduino
    one of the toughest parts was getting
    the pads in the PCB to line up with the pin
    headers on the Arduino. It took
    a set of digital calipers and a lot of time
    but the alignment was achieved. What
    was missed was the top of the USB
    port and the power barrel jack is
    higher than the pin headers. That is why
    in the PCB drawing in post #13
    ('POCADAL Main Board 201024') there
    are two leave-outs at the bottom of the board
    between S4 and S5 and between S6 and S7.

    The plan is to based on the always excellent
    feedback from the ETO forum, redesign 'POCADAL Main Board 201024'
    this Saturday and re-order a new board.

    Thanks.

    Allen in Dallas

    What PCB layout software are you using to design the board?
    Does it have a matching schematic capture program as well?

    May be a little late in the game but I ask these questions because if the schematic was captured with the software, then design changes could be sent back and forth between the schematic and board layout to keep them synchronized, making change management a lot easier. If you make a mistake, you could make the correction in one process and easily pass the changes to the other process.

    As a suggestion,
    Make one schematic of each module. This will be used as a main copy.
    Make one board layout for each module. This will be used as a main copy.
    Make one system diagram showing each module and how they interconnect. This should include any third party components like the Arduino, Power Supply, and power distribution. This will also be used as a main copy.
    Each of these documents will grow in detail as the design progresses, and should be updated regularly. Their content supersedes any other versions.
    Keep a record of any major change to any of these documents. These can be in the form of electronic notes, or printed copies.
    The records will create a "history" you can refer to in the event the reason for a change cannot be deduced.

    Anyway, I'll take a look at your newly posted drawing.
     
    Last edited:

    eTech

    Active Member
    Hello

    I've reviewed your drawing. I had some trouble making out the connections on DWG 201026 so I made my own. Please review attached for the following comments.

    1. R8 at the left side of 201026 is not needed.
    2. All resistors on this module can be 1/4W, 5%.
    3. I've added feed thru terminals to connect to the Arduino supplied 5V and GND

    Hope what I've shown makes sense.
    1603915971269.png
     
    Hello eTech and the ETO forum,

    Response to post #18:

    The PC layout software is Dip Trace by Novarm
    Link to Dip Trace home page
    It does have a Schematic Capture module.
    An attempt to master the Schematic Capture
    feature was attempted but was abandoned in the face of a steep
    learning curve. But now that a comfort level
    has been achieved with the PCB Layout domain
    will look at using the Schematic Capture.
    I can see, not only would it save time, but solve
    issues at several levels in going from schematic to PCB.

    Will repost all three module schematics and
    PCBs.

    Have had some years of element versioning
    working with software. It may be noticed
    that the drawings are always dated and some have
    revision notes like POCADAL Sensor Module
    PODACAL_12v_Sensor_mod_schematic_201023.jpg
    dated 200725 revised in Aug and Oct.
    Although it is admitted sometimes revisions
    are not always noted and will double down
    on that.

    Response to post #19:
    Will post separate LED, Sensor and
    Shield schematic and PCBs as soon as able.

    I believe this is the latest over all schematic.
    PODACAL_12v_complete_201024.jpg
    Was there another schematic of the complete
    system posted? It was thought that this
    is the latest. The bread board was
    examined and there is a red/red/orange
    resistor. But i guess it was eliminated
    and the elimination was missed.

    Oh, wait a minute. Separate 22k resistors
    are shown for each of the sensor inputs
    on schematic marked 'REF: 202026 Rev 2020/1028'.
    They are marked R1, R2, R3, R4, R5, R6, R15, R25.

    So in preparation for refactoring the
    Shield Main Board would just run through
    some of the ideas about how the Sensors
    connect to the Main Board Shield and the
    Arduino underneath. (It is realized that
    pins from the shield penetrate down from the shield
    to the Arduino for inputs on the left and
    for outputs from the Arduino to the
    DMOS array IC on the right. Right?)

    1. The wires (some of them several feet long)
    go from the two position fixed terminal blocks
    (FTBs) on the Sensor modules and are received by
    two position FTBs on the Shield marked
    'IN S1 RTN' thru 'IN S8 RTN' on schematic
    marked 'REF: 202026 Rev 2020/1028'.

    2. The 'IN S1 RTN' FTBs go to sixteen 430 ohm
    resistors and to the anode and cathode of the
    optocouplers. The emitters of the optocouplers
    go to ground. The optocoupler collectors
    go first, via traces on the shield, to the
    Arduino input pins, and second to a 22k
    resistor and then to the plus five volt
    pin of the Uno.

    This is the only part that made me scratch my
    head. 'REF: 202026 Rev 2020/1028' shows what
    is designed on the shield to be header pins
    going thru shield down to the Arduino as
    FTB1 and FTB2 (FTBs?)
    Beginning to think this just how the headers
    are marked based on the mistake I made in the PCB
    marked 'POCADAL Arduino Shield Maon(sic) 201024
    in post #17. That is, an extra set of FTBs were
    shown because I forgot to remove
    the FTBs from the shield when the optocouplers
    were moved to the shield.

    This is probably the same reason why the six input pins
    sticking down thru the shield to pins A0-A5
    on the Arduino are marked FTB3. My bad.

    Ok I get it. The big difference between
    'REF: 202026 Rev 2020/1028' and the two
    drawings in post #17 ('POCADAL...201024'
    and 'POCADAL...201026) is my drawing
    shows one 22k resistor and eTech's shows
    eight 22k resistors.

    Will
    1. Post the latest schematics and PCB
    drawing of the LED and Sensor modules.

    2. Redraw the shield PCB drawing based on
    'REF: 202026 Rev 2020/1028' and post.

    Glad I got your input before I ordered
    the shield PCB.

    Thanks.

    Allen in Dallas

    PS Sorry about the length of this post
    but I think it got us on the same path.
     

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