Rev. 1.10
86
November 26, 2019
Rev. 1.10
87
November 26, 2019
HT68FB240
USB Low Speed Flash MCU
Bit 2
SRW:
I
2
C Slave Read/Write flag
0: Slave device should be in receive mode
1: Slave device should be in transmit mode
The SRW flag is the I
2
C Slave Read/Write flag. This flag determines whether
the master device wishes to transmit or receive data from the I
2
C bus. When the
transmitted address and slave address is match, that is when the HAAS flag is set high,
the slave device will check the SRW flag to determine whether it should be in transmit
mode or receive mode. If the SRW flag is high, the master is requesting to read data
from the bus, so the slave device should be in transmit mode. When the SRW flag
is zero, the master will write data to the bus, therefore the slave device should be in
receive mode to read this data.
Bit 1
IAMWU:
I
2
C Address Match Wake-up Control
0: Disable
1: Enable
This bit should be set to "1" to enable I
2
C address match wake up from SLEEP or
IDLE Mode.
Bit 0
RXAK:
I
2
C Bus Receive acknowledge flag
0: Slave receive acknowledge flag
1: Slave do not receive acknowledge flag
The RXAK flag is the receiver acknowledge flag. When the RXAK flag is "0", it
means that a acknowledge signal has been received at the 9th clock, after 8 bits of data
have been transmitted. When the slave device in the transmit mode, the slave device
checks the RXAK flag to determine if the master receiver wishes to receive the next
byte. The slave transmitter will therefore continue sending out data until the RXAK
flag is "1" . When this occurs, the slave transmitter will release the SDA line to allow
the master to send a STOP signal to release the I
2
C Bus.
The SIMD register is used to store the data being transmitted and received. The same
register is used by both the SPI and I
2
C functions. Before the device writes data to the
SPI bus, the actual data to be transmitted must be placed in the SIMD register. After
the data is received from the SPI bus, the device can read it from the SIMD register.
Any transmission or reception of data from the SPI bus must be made via the SIMD
register.
SIMD Register
Bit
7
6
5
4
3
2
1
0
Name
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
x
x
x
x
x
x
x
x
"x" unknown