
Communication Processor Module
MOTOROLA
MPC823 USER’S MANUAL
16-415
SMC
COMMUNICATION
16
PROCESSOR
MODULE
7. Initialize the TX buffer descriptor and assume the TX data buffer is at 0x00002000 in
main memory and contains five 8-bit characters. Write 0xB000 to TX_BD_Status,
0x0005 to TX_BD_Length, and 0x00002000 to TX_BD_Pointer.
8. Write 0xFF to the SMCE–Transparent register to clear any previous events.
9. Write 0x13 to the SMCM–Transparent register to enable all possible serial
management controller interrupts.
10. Write 0x00000010 to the CIMR so that SMC1 can generate a system interrupt. The
CICR should also be initialized.
11. Write 0x3830 to the SMCMR–Transparent to configure 8-bit characters, unreversed
data, and normal operation (not loopback). Notice that the transmitter and receiver are
not enabled yet.
12. Write 0x3833 to the SMCMR–Transparent to enable the SMC transmitter and
receiver. This additional write ensures that the TEN and REN bits are enabled last.
16.11.7.16 HANDLING INTERRUPTS IN THE SMC. Follow these steps to handle an
interrupt in the serial management controller:
1. Once an interrupt occurs, read the SMCE register to find out what caused the
interrupts. The SMCE bits are usually cleared at this time.
2. Process the TX buffer descriptor to reuse it if the TX bit is set in the SMCE–
Transparent register. Extract data from the RX buffer descriptor if the RX bit is set in
the SMCE–Transparent. To transmit another buffer, simply set the R bit in the RX
buffer descriptor.
3. Clear the SMC1 bit in the CISR.
4. Execute the rfi instruction.
16.11.8 The SMC in GCI Mode
The serial management controller can be used to control the circuit interface and monitor
channels of the general circuit interface (GCI) frame. When using the SCIT configuration of
a general circuit interface, one serial management controller can handle SCIT channel 0,
and the other serial management controller can handle SCIT channel 1. The main features
of the SMC in GCI mode are as follows:
Each SMC channel supports the circuit interface and monitor channels of the GCI
(IOM-2) in ISDN applications
Two serial management controllers support the two sets of circuit interface and monitor
channels in SCIT channels 0 and 1
Full-duplex operation
Local loopback and echo capability for testing