7733 Datasheet, PDF (227/940 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER

SERIAL I/O
8.3 Clock synchronous serial I/O mode
(4) Number of transfer clock output pins (UART0)
Only in UART0, when an internal clock is selected, one pin can be selected as the transfer clock
output pin from the following pins: CLK0, CLKS0 (in common with RxD0), and CLKS1 (in common with
____ ____
CTS0/RTS0).
By this selection, data can be transmitted to the maximum of three external receiving devices. (Refer
____ ____
to Πin Table 8.3.4). In this case, since the RxD0 and CTS0/RTS0 pins function as the transfer clock
____ ____
output pins (CLK0, CLKS1), the CTS/RTS function and reception are disabled.
_____ ____
When only the CLK0 and CLKS0 pins are used as the transfer clock output pins, the P80 (CTS0/RTS0/
CLKS1) pin can be used as a programmable I/O port. (Refer to  in Table 8.3.4.)
Also, when the CLK0 and CLKS1 pins are used as the transfer clock output pins and bit 2 of the port
P8 direction register is set to “0,” data can be received from the RxD0 pin. (Refer to Ž in Table 8.3.4.)
[Setting for related registers]
q An internal clock is selected (bit 3 at address 3016 = “0”).
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q The CTS/RTS function is disabled (bit 4 at address 3416 = “1”).
q Reception is disabled (bit 2 at address 3516 = “0”). (Refer to Œ and  in Table 8.3.4.)
q Number of transfer clock output pins is selected. (bits 5 and 4 at address 6E16; Refer to Table
8.3.3.)
q Conditions for “output when not transferring” (described later) are set.
(CLKS0: bit 2 at address 1416 = “1”:
CLKS1: bit 0 at address 1416 = “1,” bit 0 at address 1216 = level at “output when not transferring”)
[Pin status]
Refer to Table 8.3.3.
Table 8.3.3 Pin functions when one transfer clock output pin is selected
Transfer clock Number of pins
output pin from which one
Functions
selection bits transfer clock
output pin is
____ ____
CTS0/RTS0/CLKS1
CLK0
RxD0/CLKS0
TxD0
b5 b4 selected
(P80)
(P81)
(P82)
(P83)
00
1
Programmable I/O port Outputs transfer clock.
0 1 Selectable ^{Programmable I/O port Outputs transfer clock.}
Programmable I/O port Outputs
g
serial data.
10
11
Programmable I/O port Output when not transferring* Outputs transfer clock.
Outputs transfer clock. Output when not transferring* g
Output when not transferring*: When the CLK polarity selection bit (bit 6 at address 3416) = “0,” the CLK0
pin outputs “H” level; when this bit = “1,” the CLK0 pin outputs “L” level.
g When bit 2 at address 1416 (port P8 direction register) = “0,” the RxD0/CLKS0 pin is in a floating state;
when this bit = “1,” the RxD0/CLKS0 pin do the processing of “output when not transferring.”
M37733MHBXXXFP
TXD0
CLKS1
CLKS0
CLK0
IN
CLK
IN
CLK
IN
CLK
Note: This is applied when the following conditions are satisfied:
•Only transmission is performed.
•Clock synchronous serial I/O mode is selected.
•An internal clock is selected.
Fig. 8.3.2 Connection example when one transfer clock output pin is selected from three pins
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7733 Group User’s Manual