uPD780065 Subseries PUM - Renesas Electronics

CHAPTER 16 SERIAL INTERFACE (SIO31)
16.3 Register to Control Serial Interface (SIO31)
The serial interface (SIO31) uses the following type of register to control functions.
• Serial operation mode register 31 (CSIM31)
(1) Serial operation mode register 31 (CSIM31)
This register is used to enable or disable SIO31’s serial clock, operation modes, and specific operations.
CSIM31 can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM31 to 00H.
Caution In 3-wire serial I/O mode, set the port mode register (PMXX) as follows. In each case, set the output
latch to 0.
• During serial clock output (master transmission or master reception)
Set P90 (SCK31) to output mode (PM90 = 0)
• During serial clock input (slave transmission or slave reception)
Set P90 to input mode (PM90 = 1)
• During transmit/transmit and receive mode
Set P91 (SO31) to output mode (PM91 = 0)
• During receive mode
Set P92 (SI31) to input mode (PM92 = 1)
Figure 16-2. Format of Serial Operation Mode Register 31 (CSIM31)
Address: FFB1H After reset: 00H R/W
Symbol 7 6 5 4 3 2 1 0
CSIM31 CSIE31 0 0 0 0 MODE1 SCL311 SCL310
CSIE31
Enable/disable specification for SIO31
Shift register operation Serial counter Port
0 Operation stop Clear Port functionNote 1
1 Operation enable Count operation enable Serial function + port functionNote 2
MODE1
Transfer operation modes and flags
Operation mode Transfer start trigger SO31 output
0 Transmit/transmit and receive mode Write to SIO31 Normal output
1 Receive-only mode Read from SIO31 Fixed at low level
SCL311 SCL310 Clock selection
0 0 External clock input to SCK31
0 1 fX/2 3 (1.05 MHz)
1 0 fX/2 4 (524 kHz)
1 1 fX/2 5 (262 kHz)
Preliminary User’s Manual U13420EJ2V0UM00
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