Figure 149. Slave Transmitter Timing Diagram - Holtek HT32F50231 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F50231/HT32F50241
Slave Transmitter Mode
Address Frame
In the 7-bit addressing mode, the ADRS bit in the I2CSR register is set after the slave device
receives the calling address which matches with the slave device address. In the 10-bit addressing
mode, the ADRS bit is set for the first time when the first header byte and the second address byte
are both matched. Note that when the second header byte is also matched, the ADRS bit will be
set again. After the ADRS bit has been set to 1, it must be cleared to 0 to continue the data transfer
process. The ADRS bit is cleared after reading the I2CSR register.
Data Frame
In the Slave transmitter mode, the TXDE bit is set to indicate that the I2CDR is empty, which
results in the SCL line being held at a logic low state. New transmission data must then be written
into the I2CDR register to continue the data transfer process. Writing a data into the I2CDR
register will clear the TXDE bit.
Receive Not-Acknowledge
When the slave device receives a Not-Acknowledge signal, the RXNACK bit in the I2CSR Register
is set but it will not hold the SCL line. Writing "1" to RXNACK will clear the RXNACK flag.
STOP Condition
When the slave device detects a STOP condition, the STO bit in the I2CSR register is set to indicate
that the I C interface transmission is terminated. Reading the I2CSR register can clear the STO flag.
2
7-bit Slave Transmitter
S Address A
TXDE
ADRS
BEH1 BEH2
10-bit Slave Transmitter
S Header A Address A
Header A
Sr
BEH1 : cleared by reading I2CSR register
BEH2 : cleared by writing I2CDR register
BEH3 : cleared by writing 1 clear for RXNACK flag, TXDE is not set when NACK is received.
BEH4 : cleared by reading I2CSR register

Figure 149. Slave Transmitter Timing Diagram

Rev. 1.00
Data1 A Data2 A
TXDE
BEH2
ADRS #1
BEH1
Data1 A
TXDE TXDE
ADRS #2
BEH1 BEH2 BEH2
402 of 486
DataN
NA
...
TXDE
RXNACK
BEH2 BEH3
Data2 A DataN
...
TXDE
BEH2
P
STO
BEH4
NA P
STO
RXNACK
BEH3 BEH4
July 31, 2018