When The Mst Is "0" (Slave Mode) - Philips CEM2100/00 Service Manual

To make the transmitter terminate transmit, clear the ACK to "0" before reading data which is 1-
word before the last data to be received. A serial bus interface circuit does not generate a clock pulse
for the acknowledge signal by clearing ACK. In the interrupt routine of end of transmission, when
the BC is set to "001" and read the data, PIN is set to "1" and generates a clock pulse for a 1-bit data
transfer. In this case, since the master device is a receiver, the SDA line on a bus keeps the high-level.
The transmitter receives the high-level signal as an ACK signal. The receiver indicates to the trans-
mitter that data transfer is complete.
After 1-bit data is received and an interrupt request has occurred, generate the stop condition to ter-
minate data transfer.
SCL pin
1
SDA pin
D7
PIN
INTSBI
interrupt request
Clear ACK to "0"
before reading SBIDBR
Figure 16-12 Termination of Data Transfer in Master Receiver Mode

16.6.3.2 When the MST is "0" (Slave mode)

In the slave mode, a serial bus interface circuit operates either in normal slave mode or in slave mode
after losing arbitration.
In the slave mode, the conditions of generating INTSBI interrupt request are follows:
• At the end of acknowledge signal when the received slave address matches to the value set by the
I2CAR
• At the end of acknowledge signal when a "GENERAL CALL" is received
• At the end of transferring or receiving after matching of slave address or receiving of "GENERAL
CALL"
A serial bus interface circuit changes to a slave mode if arbitration is lost in the master mode. And an
INTSBI interrupt request occurs when word data transfer terminates after losing arbitration. The behavior
of INTSBI interrupt request and PIN after losing arbitration are shown in Table 16-3.
Table 16-3 The Behavior of INTSBI interrupt request and PIN after Losing Arbitration
When the Arbitration Lost Occurs during Trans-
mission of Slave Address as a Master
INTSBI
interrupt
request
When the slave address matches the value set
by I2CAR, the PIN is cleared to "0" by generating
PIN of INTSBI interrupt request. When the slave
address doesn't match the value set by I2CAR,
the PIN keeps "1".
When an INTSBI interrupt request occurs, the PIN (bit 4 in the SBICRB) is reset, and the SCL pin is set
to low level. Either reading or writing from or to the SBIDBR or setting the PIN to "1" releases the SCL
pin after taking t
2 3 4
D6 D5 D4
INTSBI interrupt request is generated at the termination of word data.
.
LOW
Page 207
5 6 7 8
D3 D2 D1 D0
Set BC to "001"
before reading SBIDBR
When the Arbitration Lost Occurs during Trans-
mission of Data as a Master Transmit Mode
PIN keeps "1" (PIN is not cleared to "0").
T5CL8
1
Acknowledge signal
sent to a transmitter