
deveopmen
Intelligent I/O (Serial I/O)
Rev.B2 for proof reading
Mitsubishi Microcomputers
M32C/83 group 
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER 
272
Interrupt request
generation timing
(2) Clock asynchronous serial I/O mode (UART) (group 0 and 1)
Table 1.23.14 lists the specifications for the UART mode.
Table 1.23.14.  Specifications of UART mode
Item
Transfer data format
Specification
 Character bit (transfer data)
 Start bit
 Parity bit
 Stop bit
 When internal clock is selected (Generates the transmit/receive clock in the phase
delayed waveform output mode)
_
  Transfer speed is determined when the base timer is reset by the ch0 WG function
Transfer rate (bps) = base timer count source (frequency) / (k+2) / 2
k : values set to WG register 0
_
  Transfer clock is generated when the transfer clock in the phase delayed
waveform output mode
Transmit clock : ch3 WG function
Receive clock  : Change ch2 TM function to WG function
Detects falling edge of start bit
Changes to the WG mode when the time measurement interrupt arrives
 When external clock is selected
_
 Transfer rate (bps) = Clock input to ISCLK pin
Transmission start condition To start transmission, the following requirements must be met:
 Transmit enable bit  = 
“
1
”
 Write data to transmit buffer
Reception start condition
To start reception, the following requirements must be met:
 Receive enable bit  = 
“
1
”
 When transmitting
_
 When transmit buffer is empty, transmit interrupt cause select bit = 
“
0
”
_
 When transmission is completed, transmit interrupt cause select bit = 
“
1
”
 When receiving
_
 When data is transferred to SI/O receive buffer register
Error detection
 Overrun error
: This error occurs when the next data is ready before contents
  of  SI/O receive buffer register are read out
 Framing error
: 
This error occurs when the number of stop bits set is not detected
 Parity error
: This error occurs when if parity is enabled, the number of 1
’
s in
  parity and character bits does not match the number of 1
’
s set
Select function
 Stop bit length
: Stop bit length can be selected as 1 bit or 2 bits
 Parity
: Parity can be turned on/off
: When parity is on, odd/even parity can be selected
 LSB first/MSB first selection :
Whether transmit/receive begins with bit 0 or bit 7 can be selected
 Transmit/receive data polarity switching :
This function is reversing ISTxD port output and ISRxD port input. (All I/O data level
are reversed.)
 Data transfer bit length
 : 8 bits
 : 1 bit
 : Odd, even, or nothing selected
 : 1 bit or 2 bits selected
Transfer clock
: Transmission data length can be set between 1 to 8 bits