OneWire Search not working for mixed devices (IDFGH-11938)

[rpaulbeam]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

I'm using esp-idf 5.1.2 with ESP32-S3-DevkitC in a Windows/VS Code environment. I have 2 onewire devices (DS2408 and MAX31820) on my bus, which is just a breadboard. Using the Onewire example, it can detect either of the devices, but not both. Plugging the same "network" into a Linux SBC, both devices are detected, so I believe the wiring is correct. The ID of the DS2408 (470000003FB84629) supersedes the 31820 (0100000ED5745128), so only it is detected if both are attached.

Looking at onewire_device_iter_get_next() with the JTAG debugger, I can tell that search_direction is never 0 -- last_zero = rom_bit_index is never executed even though a discrepancy is detected. I think the issue is different device families. The problem may be that last_dispepancy is initialized as 0 and rom_bit_index is initialized as 0, so a discrepancy of the first bit will be detected as the 2nd occurrance of this discrepancy? A different implementation (esp32 bitbang onewire) initializes last_discrepancy as 64. The Analog Devices App Note initializes last discrepancy as 0, but the first bit is 1 and not 0.

[suda-morris]

@rpaulbeam Thanks for reporting! I don't have a MAX31820 before my hand, It would be very appreciated if you could submit a PR in this repo for the fix.

[rpaulbeam]

The MAX3180 is a compatible temperature sensor and it works just like the ds18b20. The problem with the search routine is a discrepancy on bit 0, which can happen with different kinds of devices. I'm not experienced with esp-idf so it took me a while to move the component from a managed component to one I can modify. I will fix over the weekend and post as suggested. Get Outlook for iOS<https://aka.ms/o0ukef>

…

________________________________ From: suda-morris ***@***.***> Sent: Saturday, January 20, 2024 4:48:00 AM To: espressif/esp-idf ***@***.***> Cc: Paul Beam ***@***.***>; Mention ***@***.***> Subject: Re: [espressif/esp-idf] OneWire Search not working for mixed devices (IDFGH-11938) (Issue #13017) @rpaulbeam<https://github.com/rpaulbeam> Thanks for reporting! I don't have a MAX31820 before my hand, It would be very appreciated if you could submit a PR in this repo<https://github.com/espressif/idf-extra-components/tree/master/onewire_bus> for the fix. — Reply to this email directly, view it on GitHub<#13017 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ARIKJB3FKKLDTUTQG32RD6LYPOHFBAVCNFSM6AAAAABCCUHWSSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSMBSGA2DMMBTGI>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[suda-morris]

Link in: espressif/idf-extra-components#298