Z8 Encore!® Motor Control Flash MCUs
Product Specification
182
5. After the first bit of the first data byte has been transferred, the I2C controller sets the
TDREbit, which asserts the transmit data interrupt.
6. The software responds to the transmit data interrupt (TDRE= 1) by loading the next
data byte into the I2CDATA Register, which clears TDRE.
7. After the data byte has been received by the master, the master transmits an Acknowl-
edge instruction (or Not Acknowledge instruction if this byte is the final data byte).
8. The bus cycles through steps 5 to 7 until the final byte has been transferred. If the soft-
ware has not yet loaded the next data byte when the master brings SCL Low to trans-
fer the most significant data bit, the slave I2C controller holds SCL Low until the data
register has been written. When a Not Acknowledge instruction is received by the
slave, the I2C controller sets the NCKIbit in the I2CISTAT Register, causing the Not
Acknowledge interrupt to be generated.
9. The software responds to the Not Acknowledge interrupt by clearing the TXIbit in the
I2CCTL Register and by asserting the FLUSHbit of the I2CCTL Register to empty the
data register.
10. When the master has completed the final acknowledge cycle, it asserts a STOPor
RESTARTcondition on the bus.
11. The slave I2C controller asserts the STOP/RESTARTinterrupt (set SPRSbit in
I2CISTAT Register).
12. The software responds to the STOP/RESTARTinterrupt by reading the I2CISTAT Reg-
ister, which clears the SPRSbit.
Slave Transmit Transaction with 10-Bit Address
The data transfer format for a master reading data from a slave with 10-bit addressing is
shown in Figure 35. The following procedure describes the I2C Master/Slave Controller
operating as a slave in 10-bit addressing mode, transmitting data to the bus master.
S Slave Address W = 0 A Slave Address A S Slave Address R = 1 A Data
1st Byte 2nd Byte 1st Byte
A
Data
A
P
Figure 35. Data Transfer Format—Slave Transmit Transaction with 10-Bit Address
1. The software configures the controller for operation as a slave in 10-bit addressing
mode.
a. Initialize the MODEfield in the I2C Mode Register for either SLAVE ONLY mode
or MASTER/SLAVE mode with 10-bit addressing.
b. Optionally set the GCEbit.
c. Initialize the SLA[7:0]bits in the I2CSLVAD Register and SLA[9:8]in the
I2CMODE Register.
I2C Master/Slave Controller
P R E L I M I N A R Y
PS024604-1005
ZILOG [ ZILOG, INC. ]
