STMP15X-SHIELD with UEXT modules

[msx_23]

Hello,

I have a STMP157-OLinuXino-LIME2 board with STMP15X-SHIELD and I am strugglibng to get UEXT-modules working, for example I have connected MOD-TC-MK2-31855 to UEXT1. But with i2cdetect does not recognize any device and the compiled sample application for MOD-TC-MK2 always says "0°C". So I think the module is not recognized at all. I am not sure with the following questions:

1. On the homepage for the shield it is mentioned that the software is "Included in OLIMAGE" and "Olimage Linux images already have overlay for this shield". Do I have to activate this somehow, or should this work out of the box with "STM32MP1-OLinuXino-LIME-bullseye-base-20220928-143706.img" ?

2. Does the MOD-TC-MK2 need some kind of seperate power supply, special configuration or something? I have just attached the two wires of a k-type thermocouple and hoped for it to work out of the box...

3. Later I also want to add other UEXT-modules too. How can I check if a module is detected at all? Is e.g. i2cdetect the correct command? Do I need any configuration?

Here is the output for i2cdetect which does not change even when I disconnect the MOD-TC-MK2:

Code Select Expand

root@stm32mp1-olinuxino-lime:/home/olimex/MOD-TC-MK2#  i2cdetect -r -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- 4d -- --
50: UU UU UU UU UU UU UU UU -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
root@stm32mp1-olinuxino-lime:/home/olimex/MOD-TC-MK2#  i2cdetect -r -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
For the shield and UEXT module to work I would expect the address 0x23 to show up somewhere...

Any help would be nice. If you need more information feel free to ask.

[LubOlimex]

There should be an option to enable an overlay for STMP15X-SHIELD. You might need to first update and upgrade the Linux image. Make sure you have established Ethernet connection and run:

apt update

then when done run:

apt dist-upgrade

and agree to upgrade. When done reboot and run the olinuxino-overlay script to enable the overlay for STMP15X-SHIELD.

[msx_23]

Ok, thanks a lot that has worked 

After the update I could get the following modules to work:

• MOD-IO2
• MOD-TC-MK2-31855

However I would like to connect a third module simultaneously via UEXT (and which is not I2C as it seems):
MOD-RS485

Is this possible at all as the Shield only has two UEXT connectors? Or do I need the UEXT splitter that is on your website?

The MOD-IO2-board is described as "stackable", does that mean that I can just connect the MOD-TC to it in a row? Or is this just meant for other MOD-IO2-modules?

When I connect MOD-IO2 to the SBC-UEXT-connector and MOD-TC to the MOD-IO2, the latter is not recognized anymore... Do you have any recommendations?

[LubOlimex]

But what you tried should work as long as each board has unique I2C address. I think by default MOD-IO2 has 0x21 while MOD-TC-MK2 has 0x23 address.

You can also use UEXTx5 with some CABLE-IDC10-15cm cables to make connections easier without soldering:

https://www.olimex.com/Products/Modules/Interface/UEXTx5/open-source-hardware

https://www.olimex.com/Products/Components/Cables/CABLE-IDC10-15cm/

About MOD-RS485 - it uses UART pins + 2 control pins that you would need to handle by software means. It might be a better idea to consider MOD-RS485-ISO since it uses I2C and is generally easier to use.

[msx_23]

Thanks for the fast answer. I also have MOD-RS485-ISO available here. But how do I send and receive data with that module? It has i2c address 0x22, but I dont know how to send/receive datait in Linux...

With the USB-RS485-Adapter USB-RS485 it was pretty straight-forward, I just had to cat/echo the file /dev/ttyUSB0 (or even better using pyserial). But what do I have to do with the MOD-RS485-ISO? I cant find an example online? It would be nice to have the basic commands as it is provided for the MOD-IO module. Can you help me here?

Additional Info 1:
I want to use half-duplex mode and have therefore closed both jumpers and only connected A, B and GND, is that correct?

Additional info 2:
The only thing I have achieved so far is that I can control the red and green LED of MOD-RS485-ISO with
i2cset -y 3 0x22 0x24 0x01 (only green on)
i2cset -y 3 0x22 0x24 0x02 (only redon)
i2cset -y 3 0x22 0x24 0x03 (both on)
I think this might have something to do with read write mode? But I still have no idea how to send/receive...


Edit:

In the meantime I got it to work with the help of the wiki:
https://www.olimex.com/wiki/MOD-RS485-ISO

I think I had some bad cable attached first, which made my communication unreliable...