Re: How to configure SERCOM and UART for ring buffer with MHC?
1. How to know the version of csp? Go to your Harmony folder and look for the "csp" folder. Inside this folder open the release_notes.md file. You should be able to see the version information of csp in the first few lines. Updating core package should download the csp v3.7.x.
2. The ring buffer feature is part of the csp package. Unless the csp package is up-to-date (v3.7.x), the ring buffer option will not be available in the MHC configurator.
3. The ring buffer mode is only available when the SERCOM USART interrupt is enabled. When STDIO is connected to SERCOM USART, the interrupt is disabled as STDIO does a blocking read/write using the SERCOM USART APIs. This means that the ring buffer functionality will not be available when STDIO is connected to SERCOM USART. Also, note that the ring buffer mode is currently not supported with UART driver.
4. As far as the documentation is concerned, there are two versions of the SERCOMx_USART_ReadCallbackRegister API. One version takes callback of type "SERCOM_USART_CALLBACK" and is available when the ring buffer is disabled. The second version takes callback of type "SERCOM_USART_RING_BUFFER_CALLBACK" and is available when the ring buffer is enabled.