Programming Model
20-22 ADSP-214xx SHARC Processor Hardware Reference
3. Send test data through the host device that can be used for calculat-
ing the baud rate of the incoming signal. A NULL character (0x00)
can be used for this purpose.
4. The baud rate can be derived from the width of timer as follows:
BAUDR = Width ÷ (8 × (number of zero data bits + 1)).
5. When using a NULL character, the number of zero data bits is 8.
Programs can also send some other pattern for this purpose. Once
the baud rate is calculated inside the timer ISR, the UART can be
programmed with the calculated baud rate.
Programming Model for DMA Transfers
The following is the general procedure for transferring data using DMA.
1. Clear the UARTTXCTL/UARTRXCTL register to zero.
2. Configure the UART DMA parameter registers (index, modify and
count).
3. Configure the UARTLCR, UARTDLL, UARTDLH, UARTIER, UARTSCR and
UARTMODE registers.
4. Enable the DMA by setting the UARTEN and DMAEN bits in the UART-
TXCTL
/UARTRXCTL registers.
Setting Up and Starting Chained DMA
To start a chain pointer DMA use the following steps.
1. Clear the chain pointer register
2. Initialize the chain pointer register with the address of the DMA
descriptor table. Set the
PCI bit if an interrupt is needed at the end
of each DMA block.
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