User’s Manual U15400EJ4V0UD
217
CHAPTER 12 SERIAL INTERFACE 1A0
12.1 Function of Serial Interface 1A0
Serial interface 1A0 has the following three modes.
Operation stop mode
3-wire serial I/O mode
3-wire serial I/O mode with automatic transmit/receive function
(1)
Operation stop mode
This mode is used when serial transfer will not be performed. It enables a reduction in power consumption.
(2)
3-wire serial I/O mode (MSB/LSB-first switchable)
This mode is used to transfer 8-bit data using three lines: a serial clock line (SCK10) and two serial data lines
(SI10 and SO10).
Because this mode supports simultaneous transmission and reception, 3-wire serial I/O mode requires less
processing time for data transfer.
Also, when using 3-wire serial I/O mode, it is possible to select whether 8-bit data transfer will start with the
MSB or LSB, so any device can be connected regardless of whether that device is designed for MSB-first or
LSB-first transfers.
3-wire serial I/O mode is useful for connecting peripheral I/O circuits and display controllers with conventional
clocked serial interfaces, such as those found in the 75XL, 78K, and 17K microcontrollers.
(3)
3-wire serial mode with automatic transmit/receive function (MSB/LSB-first switchable)
This mode has an automatic transmit/receive function in addition to the functions in (2) above.
The automatic transmit/receive function is used to transmit/receive data with a maximum of 16 bytes. This
function enables the hardware to transmit/receive data to/from the OSD (On Screen Display) device and a
device with an on-chip display controller/driver independently of the CPU, thus alleviating the software load.
12.2 Configuration of Serial Interface 1A0
Serial interface 1A0 includes the following hardware.
Table 12-1. Configuration of Serial Interface 1A0
Item
Configuration
Registers
Serial I/O shift register 1A0 (SIO1A0)
Automatic data transmit/receive address pointer 0 (ADTP0)
Control registers
Serial operation mode register 1A0 (CSIM1A0)
Automatic data transmit/receive control register 0 (ADTC0)
Automatic data transmit/receive interval specification register 0 (ADTI0)
Port mode register 2 (PM2)
Port 2 (P2)