21 i
2
C SlaVe (i2CS)
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
21-15
D0
Da_STOP: Stop Condition Detect Bit
Indicates that a stop condition or a repeated start condition is detected.
1 (R/W): Detected
0 (R/W): Not detected (default)
If a stop condition or a repeated start condition is detected while the I2CS module is selected as the
slave device (SELECTED/I2CS_ASTAT register = 1), the I2CS module sets DA_STOP to 1. At the
same time, it initializes the I
2
C communication process.
When DA_STOP is set to 1, an interrupt signal is output to the ITC if the interrupt is enabled with
BSTAT_IEN/I2CS_ICTL register. This interrupt can be used to perform a terminate handling. After
DA_STOP is set to 1, it is reset to 0 by writing 1.
i
2
C Slave access Status Register (i2CS_aSTaT)
Register name address
Bit
name
Function
Setting
init. R/W
Remarks
i
2
C Slave
access Status
Register
(i2CS_aSTaT)
0x436a
(16 bits)
D15–5 –
reserved
–
–
–
0 when being read.
D4
RXRDY
Receive data ready
1 Ready
0 Not ready
0
R
D3
TXeMP
Transmit data empty
1 Empty
0 Not empty
0
R
D2
BuSY
I
2
C bus status
1 Busy
0 Free
0
R
D1
SeleCTeD I
2
C slave select status
1 Selected
0 Not selected
0
R
D0
R/W
Read/write direction
1 Output
0 Input
0
R
D[15:5] Reserved
D4
RXRDY: Receive Data Ready Bit
Indicates that the received data is ready to read.
1 (R):
Received data ready
0 (R):
No received data (default)
When the received data is loaded to the I2CS_RECV register, RXRDY is set to 1. At the same time, an
interrupt signal is output to the ITC if the interrupt is enabled with RXRDY_IEN/I2CS_ICTL register.
This interrupt can be used to read the received data from the I2CS_RECV register.
After RXRDY is set to 1, it is reset to 0 when the I2CS_RECV register is read.
D3
TXeMP: Transmit Data empty Bit
Indicates that transmit data can be written.
1 (R):
Transmit data empty (data can be written)
0 (R):
Transmit data still stored (data cannot be written) (default)
When the transmit data written to the I2CS_TRNS register is sent, TXEMP is set to 1. At the same
time, an interrupt signal is output to the ITC if the interrupt is enabled with TXEMP_IEN/I2CS_ICTL
register. This interrupt can be used to write the next transmit data to the I2CS_TRNS register.
After TXEMP is set to 1, it is reset to 0 when data is written to the I2CS_TRNS register.
D2
BuSY: i
2
C Bus Status Bit
Indicates the I
2
C bus status.
1 (R):
Bus busy status
0 (R):
Bus free status (default)
When the I2CS module detects a start condition or detects that the SCL1 or SDA1 signal goes low,
BUSY is set to 1 to indicate that the I
2
C bus enters busy status. The slave select status whether this
module is selected as the slave device or not does not affect the BUSY status. After BUSY is set to 1, it
is reset to 0 when a STOP condition is detected.
D1
SeleCTeD: i
2
C Slave Select Status Bit
Indicates that this module is selected as the I
2
C slave device.
1 (R):
Selected
0 (R):
Not selected (default)
When the slave address that is set in this module is received, SELECTED is set to 1 to indicate that this
module is selected as the I
2
C slave device. After SELECTED is set to 1, it is reset to 0 when a stop con-
dition or a repeated start condition is detected.