I had a very strange problem the other day. An sdcard and lora module cannot work together om the same physical pins of the same spi bus of the pico. The sdcard freezes when being put in an idle state. I've sorted that by moving the lora to a separate rp2040 and sending data to it via uart. The main pico now stores the data on sdcard.
The stange thing was though, if I removed lora from the bus the sdcard worked but if I only removed Vcc from the sdcard with GND and spi pins still connected, the lora module wouldn't work. I had to physcially remove the sdcard from the bus pins to get lora to work.
I asked a well known online "oracle' about this and it suggested the spi signals intended for lora were being sinked to GND via the still connected MOSI/MISO/SCK/GND pins of the sdcard which were shared with the lora module.
Is this a reasonable explanation? As physically removing all sdcard pins from the bus solved the problem it seems like a likely explanation.
The stange thing was though, if I removed lora from the bus the sdcard worked but if I only removed Vcc from the sdcard with GND and spi pins still connected, the lora module wouldn't work. I had to physcially remove the sdcard from the bus pins to get lora to work.
I asked a well known online "oracle' about this and it suggested the spi signals intended for lora were being sinked to GND via the still connected MOSI/MISO/SCK/GND pins of the sdcard which were shared with the lora module.
Is this a reasonable explanation? As physically removing all sdcard pins from the bus solved the problem it seems like a likely explanation.
Statistics: Posted by codebrane — Wed Jun 18, 2025 11:40 am