The 83C152 is an 80C51BH based microcontroller with DMA capabilities and a high speed, multi-protocol, synchronous serial communication interface called the
Global Serial Channel (GSC). The GSC uses packetized data frames that consist of a beginning of frame (BOF) flag, address byte(s), data byte(s), a Cyclic Redundancy
Check (CRC), and an End Of Frame (EOF) flag. An example of this type of packet is shown in Figure 1. Most 80C152 users will be familiar with UARTs, another type of serial interface. Figures 1 and 2 compare the two types of frames. The UART uses
start and stop bits with a data byte between as shown in Figure 2. The 83C152 retains the standard MCSé-51 UART.
CONTENTS PAGE
INTRODUCTION? 1
GSC INITIALIZATION? 9
INITIALIZATION (PROTOCOL
DEPENDENT)? 9
Baud Rate? 9
Preamble Length? 10
Backoff Mode? 10
Interframe Space? 11
Jamming Signal? 15
Slot Time? 16
Addressing? 16
INITIALIZATIONDPROTOCOL
INDEPENDENT? 18
Clearing Collision Counter? 18
Control of the GSC? 19
Initializing DMA? 19
Initializing Counters and Pointers? 20
Enabling Receiver and Receiver
Interrupts? 20
Enabling Transmitter and Transmit
Interrupts? 21
STARTING, MAINTAINING, AND
ENDING TRANSMISSIONS? 22
STARTING, MAINTAINING, AND
ENDING RECEPTIONS? 23
SUMMARY? 24
SOFTWARE EXAMPLE? A-1
CONTROLLING THE BACKOFF
ALGORITHM? B-1
REFERENCES? C-1