Timeline for I2C returning ACK irregularly on PMBUS device
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 12 at 18:06 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Aug 4 at 8:02 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Jun 6, 2023 at 23:54 | answer | added | Lucas J | timeline score: 0 | |
| May 31, 2023 at 8:39 | comment | added | CL. | Please measure the waveforms at the PSU. | |
| May 31, 2023 at 6:16 | comment | added | Justme | Yes a 3.3V MCU can't be connected to 5V bus. Since you already did, make sure that nothing is damaged. | |
| May 31, 2023 at 5:56 | comment | added | Lucas J | The power supply is compliant with PMBus Rev 1.1 which relies on SMBus. I implemented the PMBus protocol from an online library but could not communicate with the PSU so I worked back from there trying to make i2cdetect work. I'll try back without the P82B96 following your advise. I was getting weird behaviour before with the Rpi GPIOs being 3.3V and the PSU unit 5V. | |
| May 31, 2023 at 5:55 | history | edited | Velvet | CC BY-SA 4.0 |
formatting
|
| May 31, 2023 at 5:49 | history | edited | Lucas J | CC BY-SA 4.0 |
added 105 characters in body
|
| May 31, 2023 at 5:37 | comment | added | Justme | It could be that P82B96 is also cause. Maybe bus is too long or noisy. Or it's the weird bidirectional buffering it does, as seen by the weird voltage levels. If there are other I2C buffers or risetime accelerators on bus, they may be incompatible. Simplify your system, make it work without any extra chips and tricks, such as without P82B96. | |
| May 31, 2023 at 5:34 | answer | added | DoxyLover | timeline score: 1 | |
| May 31, 2023 at 5:26 | comment | added | Justme | Show the schematics. There are some weird middle-level waveforms on the bus. Also, exceeding 100 kHz and encountering weird behaviour is not a bug; you are exceeding 100 kHz and the device is rated to 100 kHz; expect weird behaviour. Also what protocol the power supply uses? You do know that i2cdetect uses a protocol that may not work with all chips? | |
| S May 31, 2023 at 4:53 | review | First questions | |||
| May 31, 2023 at 5:55 | |||||
| S May 31, 2023 at 4:53 | history | asked | Lucas J | CC BY-SA 4.0 |