RE: Persistent Bug Issue with CONFIG_I2C and ECDSA Combination

SimonDar — Wed, 20 Dec 2023 09:27:13 GMT

Switching to UART0 for TF-M seems to have resolved the posting issue, allowing me to continue with the larger project. Thank you so much!

RE: Persistent Bug Issue with CONFIG_I2C and ECDSA Combination

Jan Tore Guggedal — Wed, 20 Dec 2023 08:41:53 GMT

Hi,

I think the issue here is that the default I2C instance on nRF5340 DK is I2C1, which collides with TF-M's use of UART1 for logging. That results in a busfault when the I2C driver tries to initialize the I2C instance on the non-secure side, as it is reserved for TF-M on the secure side.

There are (at least) two options for fixing the issue:

1. Let TF-M use UART0 for logging and share it with the application. To do that, set these to Kconfig options:

CONFIG_TFM_SECURE_UART_SHARE_INSTANCE=y

CONFIG_TFM_SECURE_UART0=y

2. Reconfigure I2C to use a different instance. In the application, create a DT overlay file called `nrf5340dk_nrf5340_cpuapp_ns.overlay` in the `boards` folder with this content:

&i2c1 {
    status = "disabled";
};

That's the first step to get the app running. Then you will have to configure I2C for some other instance.

Regards,

Jan Tore