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Issue with k20 EDMA DREQ bit

Question asked by Dinakaran Murugesan on Mar 6, 2019
Latest reply on Apr 10, 2019 by Dinakaran Murugesan

Using two UART channel. Each channel is configured with EDMA for transmission. 

Both UART channels are transmitting data simultaneously. 

The problem is getting data bytes of previously sent bytes.

It seems like EDMA is retransmitting data bytes which was already transmitted in the previous call.

 

This is observed when we run multiple ports at same time at high baud rate.

 

config:

SADDR = data_buff[];
DADDR = UART data register
NBYTES_MLOFFNO = 1
minor loop linking disabled and SCG mode disabled
CITER_ELINKNO = bytes_to_be_transmit
BITER_ELINKNO = bytes_to_be_transmit
SOFF = 1
DOFF = 0
ATTR_SSIZE = 8bit
ATTR_DSIZE = 8bit
SLAST =0
DLAST_SGA = 0
CSR_DREQ =1
CSR_INTMAJOR =1

 

Note: Using fixed priority arbitration. 

And the transfer starts after setting ERQ bit of particular channel.  

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