MPC823 datasheet(72/74 Pages) MOTOROLA

72 / 74 page

Communication Processor Module

16-450

MPC823 REFERENCE MANUAL

MOTOROLA

16.12.4.4 SPI MASK REGISTER. The 8-bit read/write SPI mask (SPIM) register has the

same bit formats as the SPIE register. If a bit in the SPIM is 1, the corresponding interrupt

in the SPIE register is enabled. If the bit is zero, the corresponding interrupt in the SPIE

16.12.5 SPI Master Programming Example

The following is an example initialization sequence using the serial peripheral interface in

master mode at high speed.

1. Configure the port B pins to enable the SPIMOSI, SPIMISO, and SPICLK pins. Write

PBPAR and PBDIR bits 30, 29, and 28 with ones and then PBODR bits 30, 29, and 28

with zeros.

2. Configure a parallel I/O pin to operate as the serial peripheral interface select pin if

needed. If PB16 is chosen, write PBODR bit 16 with a zero, PBDIR bit 16 with a one,

and PBPAR bit 16 with a zero. Then write PBDAT bit 16 with a zero to constantly

assert the select pin.

3. Write RBASE and TBASE in the SPI parameter RAM to point to the RX buffer

descriptor and TX buffer descriptor in the dual-port RAM. Assuming one RX buffer

descriptor is at the beginning of the dual-port RAM and one TX buffer descriptor

follows that RX buffer descriptor, write RBASE with 0x2000 and TBASE with 0x2008.

4. Program the CPM command register (CPCR) to execute the INIT RX AND TX

PARAMS command. Write 0x0051 to the CPCR.

5. Write 0x0001 to the SDCR to initialize the SDMA configuration register.

6. Write 0x18 to RFCR and TFCR for normal operation.

7. Write MRBLR with the maximum number of bytes per receive buffer. In this case,

assume 16 bytes, so MRBLR = 0x0010.

8. Initialize the RX buffer descriptor and assume the RX data buffer is at 0x00001000 in

main memory. Write 0xB000 to RX_BD_Status, 0x0000 to RX_BD_Length (optional),

and 0x00001000 to RX_BD_Pointer.

SPIM

BIT

FIELD

RESERVED

MIME

TXE

RES

BSY

TXB

RXB

RESET

000000

R/W

ADDR

(IMMR & 0xFFFF0000) + 0xAAA

Note: For multimaster operation, enable the SPISEL pin to internally connect to the

serial peripheral interface.

MPC823 Datasheet(PDF) 72 Page - Motorola, Inc

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