Library PN532 for nano 33 ble

karnov · August 17, 2021, 12:00am

someone says that i2c library code needs to be changed

github.com/esp8266/Arduino

I2C Clock stretching on PN532 leads to bus error (?)

opened 02:00PM - 31 Jan 16 UTC

closed 06:01PM - 18 Oct 17 UTC

ghost

type: bug component: libraries

Busy with debugging issues with a PN532 tag reader. Most of the time things are …ok, but sometimes when reading a tag, the I2C bus get's stuck. The ESP will automatically reset the PN532 and everything will be just fine after that. But what's going on with the bus error and why?. I already figured out that SDA remains low for some reason (and stays until the PN532 is reset) So I started debugging with the logic analyzer and there may be some issue due to clock stretching? I'm just guessing here... It could be that the PN532 is not ready and stretches the clock? This is what happens with a normal read from the PN532. There's a gap between start and first byte written. It's approx. 100 uSec and things run ok. ![pn532_read_no_tag](https://cloud.githubusercontent.com/assets/11584787/12702441/c238b148-c829-11e5-8c65-0b56cde43e99.png) But when the bus error appears, there's a gap of approx. 250 uSec and the first byte has an issue. It should be a zero byte but I guess somethings happening within the I2C libs... ![pn532_read_sda_error](https://cloud.githubusercontent.com/assets/11584787/12702442/c5d33472-c829-11e5-8096-dbc3ed5daa1a.png) Could my theory make any sense? If it is clock stretching, does the I2C library support what's going on here... ## <bountysource-plugin> Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/30383376-i2c-clock-stretching-on-pn532-leads-to-bus-error?utm_campaign=plugin&utm_content=tracker%2F14245935&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F14245935&utm_medium=issues&utm_source=github). </bountysource-plugin>

I can't figure out where to make this change

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Library PN532 for nano 33 ble

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