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M16C/62P Group (M16C/62P, M16C/62PT)
17.1.1 Clock Synchronous serial I/O Mode
The clock synchronous serial I/O mode uses a transfer clock to transmit and receive data. Table 17.1
lists the specifications of the clock synchronous serial I/O mode. Table 17.2 lists the registers used in
clock synchronous serial I/O mode and the register values set.
Table 17.1 Clock Synchronous Serial I/O Mode Specifications
Item
Transfer Data Format
Transfer Clock
Transmission, Reception Control
Transmission Start Condition
Reception Start Condition
Interrupt Request
Generation Timing
Error Detection
Select Function
NOTES:
1. When an external clock is selected, the conditions must be met while if the CKPOL bit in the UiC0 register = 0 (transmit data
output at the falling edge and the receive data taken in at the rising edge of the transfer clock), the external clock is in the
high state; if the CKPOL bit in the UiC0 register = 1 (transmit data output at the rising edge and the receive data taken in at
the falling edge of the transfer clock), the external clock is in the low state.
2. If an overrun error occurs, the value of UiRB register will be indeterminate. The IR bit in the SiRIC register does not change.
3. The U0IRS and U1IRS bits respectively are the bits 0 and 1 in the UCON register; the U2IRS bit is the bit 4 in the U2C1
register.
R
e
. v
2
3 .
0
S
e
p
0
, 1
2
0
0
4
R
E
J
0
9
B
0
1
8
5
0 -
2
3
0
Z
Transfer data length: 8 bits
CKDIR bit in the UiMR(i=0 to 2) register = 0 (internal clock) : fj/ 2(n+1)
• fj = f1SIO, f2SIO, f8SIO, f32SIO. n: Setting value of UiBRG register
CKDIR bit = 1 (external clock ) : Input from CLKi pin
Selectable from CTS function, RTS function or CTS/RTS function disable
Before transmission can start, the following requirements must be met
• The TE bit in the UiC1 register = 1 (transmission enabled)
• The TI bit in the UiC1 register = 0 (data present in UiTB register)
_______
• If CTS function is selected, input on the CTSi pin = L
Before reception can start, the following requirements must be met
• The RE bit in the UiC1 register = 1 (reception enabled)
• The TE bit in the UiC1 register = 1 (transmission enabled)
• The TI bit in the UiC1 register = 0 (data present in the UiTB register)
For transmission, one of the following conditions can be selected
(3)
• The UiIRS bit
UiTB register to the UARTi transmit register (at start of transmission)
• The UiIRS bit =1 (transfer completed): when the serial I/O finished sending data from
the UARTi transmit register
For reception
• When transferring data from the UARTi receive register to the UiRB register (at
completion of reception)
(2)
Overrun error
This error occurs if the serial I/O started receiving the next data before reading the
UiRB register and received the 7th bit of the next data
• CLK polarity selection
Transfer data input/output can be chosen to occur synchronously with the rising or
the falling edge of the transfer clock
• LSB first, MSB first selection
Whether to start sending/receiving data beginning with bit 0 or beginning with bit 7
can be selected
• Continuous receive mode selection
Reception is enabled immediately by reading the UiRB register
• Switching serial data logic
This function reverses the logic value of the transmit/receive data
• Transfer clock output from multiple pins selection (UART1)
The output pin can be selected in a program from two UART1 transfer clock pins that
have been set
_______ _______
• Separate CTS/RTS pins (UART0)
_________
_________
CTS0 and RTS0 are input/output from separate pins
page 164
f o
3
6
4
Specification
_______
_______
_______
= 0 (transmit buffer empty): when transferring data from the
17. Serial I/O
_______ _______
(1)
(1)
00h to FFh
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