Serial I/O (Special Modes)
177
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
Special Mode 3 (IE mode)
In this mode, one bit of IEBus is approximated with one byte of UART mode waveform.
Table 1.20.8 lists the registers used in IE mode and the register values set. Figure 1.20.9 shows the
functions of bus collision detect function related bits.
If the TxDi pin (i = 0 to 2) output level and RxDi pin input level do not match, a UARTi bus collision detect
interrupt request is generated.
Use the IFSR2A register’s IFSR26 and IFSR27 bits to enable the UART0/UART1 bus collision detect
function.
Table 1. 20. 8. Registers to Be Used and Settings in IE Mode
Register
Bit
UiTB
0 to 8
Set transmission data
UiRB
(Note3)
0 to 8
Reception data can be read
OER,FER,PER,SUM
Error flag
UiBRG
---
Set a transfer rate
UiMR
SMD2 to SMD0
Set to ‘110
2
’
CKDIR
Select the internal clock or external clock
STPS
Set to “0”
PRY
Invalid because PRYE=0
PRYE
Set to “0”
IOPOL
Select the TxD/RxD input/output polarity
UiC0
CLK1, CLK0
Select the count source for the UiBRG register
CRS
Invalid because CRD=1
TXEPT
Transmit register empty flag
CRD
Set to “1”
NCH
Select TxDi pin output mode (Note 2)
CKPOL
Set to “0”
UFORM
Set to “0”
UiC1
TE
Set this bit to “1” to enable transmission
TI
Transmit buffer empty flag
RE
Set this bit to “1” to enable reception
RI
Reception complete flag
U2IRS (Note 1)
Select the source of UART2 transmit interrupt
UiRRM (Note 1),
Set to “0”
UiLCH, UiERE
UiSMR
0 to 3, 7
Set to “0”
ABSCS
Select the sampling timing at which to detect a bus collision
ACSE
Set this bit to “1” to use the auto clear function of transmit enable bit
SSS
Select the transmit start condition
UiSMR2
0 to 7
Set to “0”
UiSMR3
0 to 7
Set to “0”
UiSMR4
0 to 7
Set to “0”
IFSR2A
IFSR26, IFSR27
Set to “1”
UCON
U0IRS, U1IRS
Select the source of UART0/UART1 transmit interrupt
U0RRM, U1RRM
Set to “0”
CLKMD0
Invalid because CLKMD1 = 0
CLKMD1,RCSP,7
Set to “0”
Note 1: Set the U0C0 and U1C1 registers bit 4 and bit 5 to “0”. The U0IRS, U1IRS, U0RRM and U1RRM bits
are in the UCON register.
Note 2: TxD2 pin is N channel open-drain output. Set the U2C0 register's NCH bit to “0”.
Note 3: Not all register bits are described above. Set those bits to “0” when writing to the registers in IEmode.
i= 0 to 2
Function