CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U13850EJ6V0UD
420
Figure 10-55. Block Diagram of CSI4
Baud rate
generator
SO4
SI4
INTCSI4
Serial clock controller
Selector
Interrupt
generator
Serial clock counter
(8-/16-bit switchable)
Variable-length I/O shift
register 4 (8-/16-bit)
SCK4
Direction controller
Internal bus
(1) Variable-length serial I/O shift register 4 (SIO4)
SIO4 is a 16-bit variable register that performs parallel-serial conversion and transmit/receive (shift operations)
synchronized with the serial clock.
SIO4 is set by a 16-bit memory manipulation instruction.
The serial operation starts when data is written to or read from SIO4, while the bit 7 (CSIE4) of variable-length
serial control register 4 (CSIM4) is 1.
When transmitting, data written to SIO4 is output via the serial output (SO4).
When receiving, data is read from the serial input (SI4) and written to SIO4.
RESET input clears SIO4 to 0000H.
Caution
Do not execute SIO4 access except for the access that becomes the transfer start trigger
during transfer operations (read is disabled when MODE4 = 0 and write is disabled when
MODE4 = 1).
After reset: 0000H R/W Address: FFFFF2E0H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
SIO4
Содержание V850/SB1
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