PN7120 driver error : "pn54x_dev_write : i2c_master_send returned -5. When probe with scope, it seems that sometime, it is ACK the write from DH.

[frank689]

Hi I have integrated PN7120 Linux driver and HAL base on AN11690. I run the NXP test apk. It is able scan and discovered the NFC credit card. However, every once awhile, I'm getting the following errors from the driver. "pn54x_dev_write : i2c_master_send returned -5. When I probe i2c bus with scope, it seems that sometimes, it is response ACK on i2c write access. 

[Kan_Li]

Hi Frank,

Error code "-5" relates to generic errno definition EIO (I/O error). Refer to errno.h - C Error Codes in Linux for more details.

Looking to the pn5xx_i2c module implementation (nxp-pn5xx/pn5xx_i2c.c at master · NXPNFCLinux/nxp-pn5xx · GitHub ), this error code is raised by the kernel I2C driver (i2c_master_send).

In a specific case, the PN7120 is not answering to I2C write command: when it is in standby state. This is expected behavior, first write command waking-up the PN7120 and second one will be answered. The MW stack (Linux or Android stack) is managing the re-transmission of the frame to handle this case.

Hope that helps,
Have a great day,
Kan

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