18 UNIVERSAL SERIAL INTERFACE (USI)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
18-31
D0
STDIF: Transmit Buffer Empty Flag Bit
Indicates the transmit data buffer status.
1 (R):
Empty
0 (R):
Data exists (default)
1 (W):
Reset to 0
0 (W):
Ignored
STDIF is set to 1 when the transmit data written to the transmit data buffer is transferred to the shift
register (when transmission starts), indicating that the next transmit data can be written to. At the same
time a transmit buffer empty interrupt request is sent to the ITC if STDIE/USI_SIE register is 1. STDIF
is reset by writing 1.
USI I
2
C Master Mode Trigger Register (USI_IMTG)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
USI I
2
C Master
Mode Trigger
Register
(USI_IMTG)
0x300460
(8 bits)
D7–5 –
reserved
–
–
–
0 when being read.
D4
IMTG
I
2
C master operation trigger
1 Trigger
0 Ignored
0
W
1 Waiting
0 Finished
R
D3
–
reserved
–
–
–
0 when being read.
D2–0 IMTGMOD
[2:0]
I
2
C master trigger mode select
IMTGMOD[2:0] Trigger mode
0x0 R/W
0x7
0x6
0x5
0x4
0x3
0x2
0x1
0x0
reserved
Receive ACK/NAK
Transmit NAK
Transmit ACK
Receive data
Transmit data
Stop condition
Start condition
Note: This register is effective only in I
2
C master mode. Configure USI to I
2
C master mode before this
register can be used.
D[7:5]
Reserved
D4
IMTG: I
2
C Master Operation Trigger Bit
Starts an I
2
C master operation.
1 (W):
Trigger
0 (W):
Ignored
1 (R):
Waiting for starting operation
0 (R):
Trigger has finished (default)
Select an I
2
C master operation using IMTGMOD[2:0] and write 1 to IMTG as the trigger. The I
2
C con-
troller controls the I
2
C bus to generate the specified operating status.
D3
Reserved
D[2:0]
IMTGMOD[2:0]: I
2
C Master Trigger Mode Select Bits
Selects an I
2
C master operation.
8.3 Trigger List in I
Table 18.
2
C Master Mode
IMTGMOD[2:0]
Trigger
0x7
Reserved
0x6
ACK/NAK reception
0x5
NAK transmission
0x4
ACK transmission
0x3
Data reception
0x2
Data transmission
0x1
Stop condition
0x0
Start condition
(Default: 0x0)