R01UH0092EJ0110 Rev.1.10
Page 507 of 807
Jul 31, 2012
M16C/64C Group
23. Serial Interface UARTi (i = 0 to 2, 5 to 7)
23.3.5
Special Mode 3 (IE Mode)
In this mode, 1 bit of IEBus is approximated by 1 byte of UART mode waveform.
Table 23.23 lists the Registers Used and Settings in IE Mode. Figure 23.34 shows the Bus Collision
Detect Function-Related Bits.
If the TXDi pin (i = 0 to 2, 5 to 7) output level and RXDi pin input level do not match, a UARTi bus
collision detect interrupt request is generated.
Use bits IFSR26 and IFSR27 in the IFSR2A register to enable the UART0/UART1 bus collision detect
function.
Table 23.23
Registers Used and Settings in IE Mode
(1)
Register
Bits
Function
UiTB
0 to 8
Set transmission data.
0 to 8
Reception data can be read.
OER, FER, PER, SUM
Error flag
UiBRG
0 to 7
Set bit rate.
UiMR
SMD2 to SMD0
Set to 110b.
CKDIR
Select internal clock or external clock.
STPS
Set to 0.
PRY
Disabled because PRYE is 0
PRYE
Set to 0.
IOPOL
Select the TXD and RXD input/output polarity.
UiC0
CLK1, CLK0
Select the count source for the UiBRG register.
CRS
Disabled because CRD is 1
TXEPT
Transmit register empty flag
CRD
Set to 1.
NCH
Select TXDi pin output format.
(3)
CKPOL
Set to 0.
UFORM
Set to 0.
UiC1
TE
Set to 1 to enable transmission.
TI
Transmit buffer empty flag
RE
Set to 1 to enable reception.
RI
Reception complete flag
UjIRS
(2)
Select the source of UARTj transmit interrupt.
UjRRM
(2)
, UiLCH, UiERE
Set to 0.
UiSMR
0 to 3, 7
Set to 0.
ABSCS
Select the sampling timing to detect a bus collision.
ACSE
Set to 1 to use the auto clear function of the 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.
UCON
U0IRS, U1IRS
Select the source of UART0/UART1 transmit interrupt.
U0RRM, U1RRM
Set to 0.
CLKMD0
Disabled because CLKMD1 is 0
CLKMD1, RCSP, 7
Set to 0.
i = 0 to 2, 5 to 7; j = 2, 5 to 7
Notes:
1.
This table does not describe a procedure.
2.
Set bits 4 and 5 in registers U0C1 and U1C1 to 0. Bits U0IRS, U1IRS, U0RRM, and U1RRM are in the
UCON register.
3.
The TXD2 pin is N-channel open drain output. Nothing is assigned to the NCH bit in the U2C0 register. If
necessary, set it to 0.
4.
Set the bits not listed above to 0 when writing to registers in IE mode
.
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