aws_iot with crypto chip causes I2C error (ESP-IDF v3.2.2)

[GerryTitan]

Hello,

I am trying to configure the "aws_iot" example to work with an external crypto chip (ATECC608A by Microchip). This chip stores the private key and can perform the required ECDSA signature operations for mutual authentication. I have already configured the chip to communicate over I2C, and I am now currently trying to overwrite the mbedtls_ecdsa_sign function to offload the signature process to the external chip. However, any kind of traffic over the I2C bus produces the following error:

Code: Select all

E (8363) i2c: /home/bryan/esp/esp-idf/components/driver/i2c.c:1243 (i2c_master_cmd_begin):i2c number error

Again, I should stress that I2C communication normally works with this chip. I have not changed anything in hardware. It just seems that when I call the function "aws_iot_mqtt_connect(&client, &connectParams)" (from the subscribe_publish.c file in the example), then the communication breaks down. Does anyone know what is happening here?

Thanks in advance for the help.

[GerryTitan]

Hello again. It turns out that mbedtls and the aws_iot example are not the cause of the problem. It seems that calling xTaskCreatePinnedToCore is what causes the I2C problems to occur. Maybe it is a sync issue? I'm not really sure. Does anyone have any suggestions?

[jwwest]

Hi Gerry,
I am trying to get my project setup to use the ATECC608A device for Google IoT, but I have not been able to find any details on how to go about this. I was hoping you might be able to share some of your secrets on this.

Thanks in advance.

-Josh