Solidrun confirmed the feasibility of this feature and provided us with some indications. One of our engineer is currently developing a daughter board providing the access to a second CAN interface.

CAN¶

Patch provided on our public gitlab: https://git.iot.bzh/saft/datahub/liquidsense/liquidsense-linux-support/-/blob/main/0050-LiquidSense-enable-CAN-LiquidSense-4-MHz-clock.patch

The secondary can interface is available as `can1`.

This patch uses the LiquidSense dedicated 4MHz quartz to clock the
secondary CAN controller bus.

Another patch has to be created if we want to use the 24Mhz SolidSense clock (which is used by SolidSense CAN controller).
This modification involve soldering a resistor to link the LiquidSense CAN controller to this clock.

GPIO expander¶

Patch provided on our public gitlab: https://git.iot.bzh/saft/datahub/liquidsense/liquidsense-linux-support/-/blob/main/0051-LiquidSense-enable-GPIO-expander.patch

The expander appears as /dev/gpiochip5.

It provides 8 I/Os which are labelled and set as inputs by default.

Bits 0 to 3 are classic IOs:
- liquidsense:es1 is bit 0 (untested)
- liquidsense:es2 is bit 1 (untested)
- liquidsense:es3 is bit 2
- liquidsense:es4 is bit 3

Bits 4 to 7 match a dip switch:
- liquidsense:sw1-4 is bit 4
- liquidsense:sw1-3 is bit 5
- liquidsense:sw1-2 is bit 6
- liquidsense:sw1-1 is bit 7

GPIO expander is available on I2C2 bus at address 0x20 (issue in liquidsense manual providing address 0x18)