The 83C152 is an 80C51BH based microcontroller with DMA capabilities and a high speed, multi-protocol, synchronous serial communication interface called theGlobal 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 RedundancyCheck (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 usesstart and stop bits with a data byte between as shown in Figure 2. The 83C152 retains the standard MCSÉ-51 UART.CONTENTS PAGEINTRODUCTION 1GSC INITIALIZATION 9INITIALIZATION (PROTOCOLDEPENDENT) 9Baud Rate 9Preamble Length 10Backoff Mode 10Interframe Space 11Jamming Signal 15Slot Time 16Addressing 16INITIALIZATIONÐPROTOCOLINDEPENDENT 18Clearing Collision Counter 18Control of the GSC 19Initializing DMA 19Initializing Counters and Pointers 20Enabling Receiver and ReceiverInterrupts 20Enabling Transmitter and TransmitInterrupts 21STARTING, MAINTAINING, ANDENDING TRANSMISSIONS 22STARTING, MAINTAINING, ANDENDING RECEPTIONS 23SUMMARY 24SOFTWARE EXAMPLE A-1CONTROLLING THE BACKOFFALGORITHM B-1REFERENCES C-1