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M16C/62P Group (M16C/62P, M16C/62PT)
Table 17.14 STSPSEL Bit Functions
Function
Output of SCLi and SDAi Pins
Star/Stop Condition Interrupt
Request Generation Timing
(1) When slave
CKDIR=1 (external clock)
STSPSEL bit 0
SCLi
SDAi
(2) When master
CKDIR=0 (internal clock), CKPH=1 (clock delayed)
STSPSEL bit
SCLi
SDAi
Figure 17.24 STSPSEL Bit Functions
17.1.3.3 Arbitration
Unmatching of the transmit data and SDAi pin input data is checked synchronously with the rising
edge of SCLi. Use the ABC bit in the UiSMR register to select the timing at which the ABT bit in the
UiRB register is updated. If the ABC bit = 0 (updated bitwise), the ABT bit is set to "1" at the same time
unmatching is detected during check, and is cleared to "0" when not detected. In cases when the ABC
bit is set to "1", if unmatching is detected even once during check, the ABT bit is set to "1" (unmatching
detected) at the falling edge of the clock pulse of 9th bit. If the ABT bit needs to be updated bytewise,
clear the ABT bit to "0" (undetected) after detecting acknowledge in the first byte, before transferring
the next byte.
Setting the ALS bit in the UiSMR2 register to "1" (SDA output stop enabled) factors arbitration-lost to
occur, in which case the SDAi pin is placed in the high-impedance state at the same time the ABT bit
is set to "1" (unmatching detected).
R
e
. v
2
3 .
0
S
e
p
0
, 1
2
0
0
4
R
E
J
0
9
B
0
1
8
5
0 -
2
3
0
Z
Output of transfer clock and
data
Output of start/stop condition is
accomplished by a program
using ports (not automatically
generated in hardware)
Start/stop condition detection
1st 2nd 3rd 4th 5th 6th 7th 8th 9th bit
Start condition
detection interrupt
Set to "1" in
Set to "0" in
a program
a program
Set STAREQ=1
(start)
Start condition
detection interrupt
page 187
f o
3
6
4
STSPSEL = 0
1st 2nd 3rd 4th 5th 6th 7th 8th 9th bit
Set STPREQ=1
(start)
STSPSEL = 1
Output of a start/stop condition
according to the STAREQ,
RSTAREQ and STPREQ bit
Finish generating start/stop condi-
tion
Stop condition
detection interrupt
Set to "1" in
Set to "0" in
a program
a program
Stop condition
detection interrupt
17. Serial I/O
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