4 channel 4-20mA receiver

Hardware
1

Hello,

I am having problems with the 4 channel 4-20mA receive module. Sometimes it works most of the time it doesn’t. Does anybody have experience with this module?. The I2C codes are sent as i confirmed with logic analyser but noting is being sent back from the MCP3428 IC. Could it be a conception problem as i don’t see no decoupling capacitor near the MCP3428. Any help would be greatly appreciated.

Thank you!

2

Hi,

  1. does it send wrong value or no values at all?
  2. what is the i2c cable length
  3. does your master device has pull ups?

Thanks

3

Hello,

  1. no value sent back

  2. cable under 10 inches

  3. I use a i2c level shifter between master (Cortex M0) and slave (MCP3428) ,
    the pull ups are ON on the 5V slave side but i have no pull ups on the 3.3V
    master side of things. I tried to put some on the 3.3V side but no change.

    This is the level shifter that is use:
    https://abra-electronics.com/robotics-embedded-electronics/breakout-boards/level-shifters-and-expanders/am-137-4-way-i2c-bi-directional-logic-level-converter-5vdc-3.3vdc-for-microcontrollers-and-modules.html

4

the level shifter could be the issue. I will recommend using a full i2c level shifter.

I never used such transistor based level shifter with i2C but i have used these with UART and haven’t had much luck with these.

do you happen to know if your master device is 5V tolerant or not?

5

The feather M0 from Adafruit is the master device that contains a ATSAMD21G18 Cortex M0 unit
and i think it is 5V tolerant (5V output with pull-ups) but need more investigation on that will post back.
Anyway i tried with direct connections and it didn’t work… i will try again.

thank you