14. Serial I/O
puorG92/C61M
page 203
854fo7002,03.raM21.1.veR
2110-1010B90JER
Table 14.14 STSPSEL Bit Functions
Figure 14.25 STSPSEL Bit Functions
Function
Output of SCL2 and SDA2 pins
Start/stop condition interrupt
request generation timing
STSPSEL = 0
Output transfer clock and data/
Program with a port determines
how the start condition or stop
condition is output
Start/stop condition are detec-
ted
STSPSEL = 1
The STAREQ, RSTAREQ and
STPREQ bit determine how the
start condition or stop condition is
output
Start/stop condition generation
are completed
14.1.3.3 Arbitration
Unmatching of the transmit data and SDA2 pin input data is checked synchronously with the rising
edge of SCL2. Use the ABC bit in the U2SMR register to select the timing at which the ABT bit in the
U2RB register is updated. If the ABC bit is set to 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 U2SMR2 register to 1 (SDA2 output stop enabled) causes arbitration-lost to
occur, in which case the SDA2 pin is placed in the high-impedance state at the same time the ABT bit
is set to 1 (unmatching detected).
SDA2
(1) In slave mode,
CKDIR is set to 1 (external clock)
SCL2
SDA2
Start condition detection
interrupt
Stop condition detection
interrupt
(2) In master mode,
CKDIR is set to 0 (internal clock), CKPH is set to 1(clock delayed)
SCL2
Set STAREQ
to 1 (start)
Set STPREQ
to 1 (start)
STPSEL bit
0
STPSEL bi
t
Set to 1 by
program
Set to 0 by
program
Set to 1 by
program
Set to 0 by
program
1st 2nd 3rd 5th 6th 7th 8th 9th bit
1st 2nd 3rd 5th 6th 7th 8th 9th bit
4th
4th
Start condition detection
interrupt
Stop condition detection
interrupt
To Next Page
Loading...
Need help?
General
