ST9 datasheet(108/146 Pages) STMICROELECTRONICS

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ST9 USER GUIDE

Table 10.

SCI.C Functions

4.8.2.4.3 SCI Files using DMA in the Loopback Mode

The SCI function file is <sci\appli3\sci.c> and contains 5 functions that are initialized for

sending 26 bytes from memory to the serial link.

The SCI is in Loopback mode, so that the bytes sent are then received by the SCI and stored

in the register file (from R16).

It uses DMA channels:

– From memory to peripheral for the transmission

– From the peripheral to the register file to receive the bytes.

No ports are used.

4.8.2.4.4 SCI Files using Character Matching

The SCI function file is <sci\appli4\sci.c> and contains 5 functions that are initialized for re-

ceiving data on the input pin of the SCI and it only reacts when it receives character

SCI_MATCH (defined in sci.h).

Port used: Rx (S0IN)

FUNCTION

DESCRIPTION AND COMMENTS

void INIT_SCI_DMA(void);

Initialization of general parameters dedicated to the SCI:

- Baud Rate Generator: 9600 bauds.

- Characters: Eight data bits, one stop bit, odd parity.

- Pins...

The baud rate generator must be initialized following this structure

(BRGHR first and BRGLR at the end).

Initialization of the IT: vector, priority.

Initialization of DMA in transmission

void START_SendDMA(un-

signed char * TransmitBuff-

erMem, unsigned int

SCI_count);

After a few extra initialization, the transmission starts by loading data reg-

ister(TXBR) with the first value to send.

void

INTSCI_TransmitEOB(void)

;

Interrupt subroutine which occurs when a whole block of data has been

transferred using DMA.

In fact, the buffer “table” is sent three times and then DMA is disabled.

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