Rainbow Electronics ATAR862-3 - Manual (Page 76)

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ATAR862-3
4556B–4BMCU–02/03
Serial Interface Status and
Control Register (SISC) Primary register address: "A"hex
Serial Transmit Buffer (STB) –
Byte Write Primary register address: "9"hex
T he STB is the transmit buffer of the SSI. The SSI transfers the transmit buffer into the shift regi s-
ter and star ts shifting with the most significant bit.
Serial Receive Buffer (SRB) –
Byte Read Primary register address: "9"hex
T he SRB is the receive buffer of the SSI. The shift register clocks serial data in (most significant
bit first) and loads content into the receive buffer when complete telegram has been received.
Bit 3 Bit 2 Bit 1 Bit 0
Write MCL RACK SIM IFN Reset value: 1111b
Read - - - TACK ACT SRDY Reset value: xxxxb
MCL M ulti- C hip L ink activation
MCL = 1,multi-chip link disabled. This bit has to be set to "0" during
transactions to/from EEPROM of the M44C892
MCL = 0, connects SC and SD additionally to the internal multi-chip link pads
RACK R eceive ACK nowledge status/control bit for MCLmode
RACK = 0, transmit acknowledge in next receive telegram
RACK = 1, transmit no acknowledge in last receive telegram
TACK T ransmit ACK nowledge status/control bit for MCL mode
TACK = 0, acknowledge received in last transmit telegram
TACK = 1, no acknowledge received in last transmit telegram
SIM S erial I nterrupt M ask
SIM = 1, disable interrupts
SIM = 0, enable serial interrupt. An interrupt is generated.
IFN I nterrupt F u N ction
IFN = 1, the serial interrupt is generated at the end of telegram
IFN = 0, the serial interrupt is generated when the SRDY goes low (i.e., buffer
becomes empty/full in transmit/receive mode)
SRDY S erial interface buffer R ea DY status flag
SRDY = 1, in receive mode: receive buffer empty
in transmit mode: transmit buffer full
SRDY = 0, in receive mode: receive buffer full
in transmit mode: transmit buffer empty
ACT Transmission ACT ive status flag
ACT = 1, transmission is active, i.e., serial data transfer. Stop or start conditions
are currently in progress.
ACT = 0, transmission is inactive
First write cycle Bit 3 Bit 2 Bit 1 Bit 0 Reset value: xxxxb
Second write cycle Bit 7 Bit 6 Bit 5 Bit 4 Reset value: xxxxb
First read cycle Bit 7 Bit 6 Bit 5 Bit 4 Reset value: xxxxb
Second read cycle Bit 3 Bit 2 Bit 1 Bit 0 Reset value: xxxxb