Hardware SDS011 restarter for NAM 0.3

During our extensive use of SDS011 in NAM sensors we encountered some problems. Sometimes SDS011 hangs and become unresponsive. UART communication doesn’t work at all. Our research shows that the reason is probably because of bugs in it’s firmware. Only working method of restoring communication is to power off the SDS011 for couple seconds. Because in remote location it’s usually impossible to cut the power off, we design this module to automate this task.

This module is plugged directly to EXT port of Nettigo Air Monitor 0.3. On board you will find PCF8574TS communicating via I2C on 0x26 address. Channel P0 controls power delivered to SDS011 connector. Ports P1-P7 may be used for other purposes in future as GPIO over I2C.

Compatibility

• The module is compatible with all NAM versions equipped with an EXT connector (from version 0.3.2 and above).
• The module is compatible with HECA and HECA 2.
• The module is compatible with the LED bar.
• In the standard configuration, the module CANNOT be used together with the 4x20 LCD screen. It is possible to use IDC16 tape to connect the module and hot glue for mechanical assembly, but this is untested and requires a bit of DIY :)
• The module has an EXT pass through connector, so theoretically you can still use CO2 sensors and GPS receivers, of course, if you find a place for them in the enclosure.

Links:

• Technical documentation
• Assembly instruction (currently only in Polish)