CHAPTER 12 BIT SEQUENTIAL BUFFER
User’s Manual U14826EJ5V0UD
134
12.4 Bit Sequential Buffer Operation
Set as follows to operate the bit sequential buffer.
<1> Set values to bit sequential buffer 10 data registers L and H (BSFRL10, BSFRH10)
<2> Set the bit sequential buffer to operation enabled (BSFE10 = 1)
If the LSB of BSFRL10 is being output at P20/BSFO/TMO, set P20 to output mode (PM20 = 0) and the
output latch of P20 to 0
<3> Start the clock operation
If the clock is input before the bit sequential buffer starts operation, the output time of the start bit may be shorter
than one cycle of the clock when output commences, as shown in the figure below.
2AAAH
0AAAH
5555H
1555H
t0
t1
t2
t1< t0
t2 = t0
BSFE10
Timer 40
match signal
BSFRL10,
BSFRH10
Bit sequential
buffer output
Figure 12-4 shows the operation timing of the bit sequential buffer.
Figure 12-4. Operation Timing of Bit Sequential Buffer
2AAAH
0AAAH
1555H
BSFE10
Timer 40
match signal
BSFRL10,
BSFRH10
Bit sequential
buffer output
Undefined
5555H
×
555H
×
2AAH
Cautions 1. Even if data is written to the data register while the bit sequential buffer is operating, the
shift clock (timer 40 match signal) will not stop. Data should therefore be written to the
data register when the shift clock is low level.
2. The value of the data register is undefined after a shift.
Remark
×
: Undefined