Z8F1601 Datasheet, PDF (131/246 Pages) Zilog, Inc. – Z8 Encore Microcontrollers with Flash Memory and 10-Bit A/D Converter

Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
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2. The I²C Controller waits for the slave to send an Acknowledge (by pulling the SDA
signal Low). If the slave pulls the SDA signal High (Not-Acknowledge), the I²C
Controller sends a Stop signal.
3. If the slave needs to service an interrupt, it pulls the SCL signal Low, which halts I²C
operation.
4. If there is no other data in the I²C Data register or the STOP bit in the I²C Control
register is set by software, then the Stop signal is sent.
Figure 79 illustrates the data transfer format for a 7-bit addressed slave. Shaded regions
indicate data transferred from the I²C Controller to slaves and unshaded regions indicate
data transferred from the slaves to the I²C Controller.
S ^{Slave Address W=0 A}
Data
A
Data
A
Data A/A P
Figure 79. 7-Bit Addressed Slave Data Transfer Format
The data transfer format for a transmit operation on a 7-bit addressed slave is as follows:
1. Software asserts the IEN bit in the I²C Control register.
2. Software asserts the TXI bit of the I²C Control register to enable Transmit interrupts.
3. The I²C interrupt asserts, because the I²C Data register is empty
4. Software responds to the TDRE bit by writing a 7-bit slave address followed by a 0
(write) to the I²C Data register.
5. Software asserts the START bit of the I²C Control register.
6. The I²C Controller sends the START condition to the I²C slave.
7. The I²C Controller loads the I²C Shift register with the contents of the I²C Data
register.
8. After one bit of address has been shifted out by the SDA signal, the Transmit interrupt
is asserted.
9. Software responds by writing the contents of the data into the I²C Data register.
10. The I²C Controller shifts the rest of the address and write bit out by the SDA signal.
11. The I²C slave sends an acknowledge (by pulling the SDA signal low) during the next
high period of SCL. The I²C Controller sets the ACK bit in the I²C Status register.
12. The I²C Controller loads the contents of the I²C Shift register with the contents of the
I²C Data register.
13. The I²C Controller shifts the data out of via the SDA signal. After the first bit is sent,
the Transmit interrupt is asserted.
PS017609-0803
I2C Controller