[craigbeal]

in reply to: Missing information on MPU Digital Inputs #19880

A bit of additional debugging information: I shut off both DIP switches and probed the left side solder connection of them with a multi-meter. I got ~1.4 volts. I swapped CM4 boards since I had a spare; same voltage measurement. I probed when the CM4 was off as well, 0 volts on the pull-up DIP solder connection. Not sure where to trace any further back in the system. If you can provide some guidance, I’m happy to keep checking voltages and connections.

[craigbeal]

in reply to: RS232 vs RS485 Settings #19879

OK, thanks for confirming. I think this explains the photo I sent on my other thread with the extra wires added to the board. I only need RS232, but wanted to make sure I didn’t have the switch set incorrectly.

<This issue is resolved.>

[craigbeal]

in reply to: Missing information on MPU Digital Inputs #19877

Yes, measuring 1.5V on the external screw terminal. I’ve got only the MPU DI-10K-PU switch moved to the left (the “on” position). I just disconnected all of the wires on the MPU DI pins (C3-59,60,19,20,71,72,31,32) and I still have low voltage between GND and any one of these pins. Is there anything else that could be loading the subsystem? Or is it possible that my CM4 is actually running off of this low voltage coming from the power supply? I measure 4.83 volts on the leads of the potentiometers that are being run off of the FlexBench 5 volt rail, if this is helpful. (V_batt is around 13.3 volts.)

As an aside, I’ve attached a picture of my FlexBench board that has a bit of corrected wiring. I’m assuming this is not related, but worth mentioning.

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[craigbeal]

in reply to: Missing information on MPU Digital Inputs #19871

Adding a bit more information, it appears that my FlexBench MPU is pulling the pins “up” to about 1.5 volts, which is actually not enough to read the pin as high according to the following page (https://www.audesseinc.com/resources/flexcase-s/digital-input-guide/). I’ve also found that a switch that grounds MPU DI7 also drags DI8 down by a substantial percentage. I’m double-checking that none of this is related to my circuitry, but so far I haven’t found any issues.

[craigbeal]

in reply to: Missing information on MPU Digital Inputs #19864

Sorry to revive an old thread, but I think it’s most pertinent to raise the question here. After looking into this for a bit, I’ve realized that I don’t know what voltage the pull-up resistor pulls the voltage *to*. It would be really helpful if you could add more detail to the Digital Inputs page, perhaps making separate sections for the MCU and MPU units since the DIO systems are very different on each of these units.

[craigbeal]

in reply to: Missing information on MPU Digital Inputs #18460

Hi Sandeep,

I believe that most of this information was previously available via the Input/Output page. However, I still do not see any info about the GPIO pins on the MPU, which was my specific need. Thanks in advance.

[craigbeal]

in reply to: No data from CM4 ADC chip SPI #15604

OK, that all makes sense. Confirmed the same behavior (SPI returning 0xFF on both bytes of all channels) on both CM4 boards plugged into the same FlexCase chassis (either chassis). The chassis is not connected to anything when doing this text. The boot config file matches (for an FCS1.1 with CM4). SPI works fine when pulling data from the IMU chip. Next steps?

• This reply was modified 2 years ago by craigbeal.

[craigbeal]

in reply to: No data from CM4 ADC chip SPI #15600

Can you post a valid /boot/config.txt for reference?

I’ve uploaded the current Empty_Project to the MCU after commenting out the MCU-MPU SPI transmission blocks and building it. I used the r1.5 samples, which seems to be different by one line in the System Start block, but I’m not quite sure what “RCM->RPC = 0x1002” does in this context. Other than that, the MCU should not be transmitting, and the MPU is not requesting data over SPI.

On the MPU side, I did use the two CM4’s in their own individual FlexCase chassis as opposed to swapping them. I had made an ADC check python script very similar to yours (except with the loop unrolled) and I was not seeing anything on any channel, other than the fact that one system gave me all high bytes over SPI (0xFF) and the other gave me all low (0x00). I’ll give the swapping CM4’s a try.

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