M30620FCAFP datasheet(143/274 Pages) MITSUBISHI

143 / 274 page

Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

UART2 Special Mode Register 2

143

Bit 4 of the UART2 special mode register 2 (address 037616) is used as the UART2 initialization bit.

Setting this bit to “1”, and when the start condition is detected, the microcomputer operates as follows.

(1) The transmission shift register is initialized, and the content of the transmission register is transferred

to the transmission shift register. This starts transmission by dealing with the clock entered next as the

first bit. The UART2 output value, however, doesn’t change until the first bit data is output after the

entrance of the clock, and remains unchanged from the value at the moment when the microcomputer

detected the start condition.

(2) The reception shift register is initialized, and the microcomputer starts reception by dealing with the

clock entered next as the first bit.

(3) The SCL wait output bit turns to “1”. This turns the SCL pin to “L” at the falling edge of the ninth bit of

the clock.

Starting to transmit/receive signals to/from UART2 using this function doesn’t change the value of the

transmission buffer empty flag. To use this function, choose the external clock for the transfer clock.

Bit 5 of the UART2 special mode register 2 (037616) is used as the SCL pin wait output bit 2. Setting this

bit to “1” with the serial I/O specified allows the user to forcibly output an “1” from the SCL pin even if

UART2 is in operation. Setting this bit to “0” frees the “L” output from the SCL pin, and the UART2 clock

is input/output.

Bit 6 of the UART2 special mode register 2 (037616) is used as the SDA output disable bit. Setting this bit

to “1” forces the SDA pin to turn to the high-impedance state. Refrain from changing the value of this bit

at the rising edge of the UART2 transfer clock. There can be instances in which arbitration lost detecting

flag is turned on.

M30620FCAFP Datasheet(PDF) 143 Page - Mitsubishi Electric Semiconductor