Z8FMC16100 Series Flash MCU
Product Specification
181
7. The software responds by reading the I2CISTAT Register, finding the RDRFbit = 1,
and then reading the I2CDATA Register, which clears the RDRFbit. If the software can
accept only one more data byte, it sets the NAKbit in the I2CCTL Register.
8. The master and slave loops through steps 5 to 7 until the master detects a Not
Acknowledge instruction or runs out of data to send.
9. The master sends the STOPor RESTARTsignal on the bus. Either of these signals can
cause the I2C controller to assert the STOP interrupt (the STOPbit = 1 in the
I2CISTAT Register). Because the slave received data from the master, the software
takes no action in response to the STOP interrupt other than reading the I2CISTAT
Register to clear the STOPbit.
Slave Transmit Transaction with 7-bit Address
The data transfer format for a master reading data from a slave in 7-bit address mode is
shown in Figure 37. The procedure that follows describes the I2C Master/Slave Controller
operating as a slave in 7-bit addressing mode and transmitting data to the bus master.
S
Slave Address
R = 1
A
Data
A
Data
A
P/S
Figure 34. Data Transfer Format—Slave Transmit Transaction with 7-bit Address
1. The software configures the controller for operation as a slave in 7-bit addressing
mode, as follows.
a. Initialize the MODEfield in the I2C Mode Register for either SLAVE ONLY mode
or MASTER/SLAVE mode with 7-bit addressing.
b. Optionally set the GCEbit.
c. Initialize the SLA[6:0]bits in the I2C Slave Address Register.
d. Set IEN= 1 in the I2C Control Register. Set NAK= 0 in the I2C Control Register.
2. The master initiates a transfer, sending the address byte. The SLAVE mode I2C con-
troller finds an address match and detects that the R/W bit = 1 (read by the master
from the slave). The I2C controller acknowledges, indicating that it is ready to accept
the transaction. The SAMbit in the I2CISTAT Register is set to 1, causing an interrupt.
The RDbit is set to 1, indicating a Read from the slave.
3. The software responds to the interrupt by reading the I2CISTAT Register, thereby
clearing the SAMbit. Because RD= 1, the software responds by loading the first data
byte into the I2CDATA Register. The software sets the TXIbit in the I2CCTL Register
to enable transmit interrupts. When the master initiates the data transfer, the I2C con-
troller holds SCL Low until the software has written the first data byte to the
I2CDATA Register.
4. SCL is released and the first data byte is shifted out.
PS024604-1005
P R E L I M I N A R Y
Slave Transactions
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