The MIXMRT1064 datasheet states for LPUART, BAUD[RIDMAE] that setting this bit will generate a DMA request. DMA request generated when STAT[IDLE] is asserted.
A DMA interrupt does not occur for this condition. Instead, an 0xFF is put in the buffer, as stated in the datasheet, DATA=0x000_33FF.
The DMA does not interrupt on RX idle, but only on RX DMA buffer full.
There are many postings about how the DMA, UART, and RX idle do not play well together.
Seems RIDMAE is useless.
Am I missing something?
If an interrupt is required on idle line this can be configured in LPUARTx_CTRL, which can be used to signal that DMA reception of a block of data has completed.
RIDMAE has been added to the LPUARTs in the i.MX RT (the LPUART version in the Kinetis parts, for example, doesn't have this) and although its behavior is described I don't know what its general practical use is - possibly it was added due to a specific customer requirement(?)
[uTasker project developer for Kinetis and i.MX RT]
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