Just a quick clarification....
From the SDK, the rxSize is described as the number of bytes to receive. Shouldn't it be the maximum number of bytes to receive???
* @param instance LPUART instance number
* @param rxBuff buffer containing 8-bit read data chars received
* @param rxSize the number of bytes to receive
* @return An error code or kStatus_LPUART_Success
lpuart_status_t LPUART_DRV_ReceiveData(uint32_t instance, uint8_t * rxBuff, uint32_t rxSize);