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CHAPTER 11 CLOCK OUTPUT CONTROLLER
User’s Manual U19780EJ2V0UD
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(2) Port mode register 4 (PM4)
This register sets port 4 input/output in 1-bit units.
When using the P42/PCL/SSI10/INTP9 pin for clock output, clear PM42 and the output latches of P42 to 0.
PM4 is set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets PM14 to FFH.
Figure 11-3. Format of Port Mode Register 4 (PM4)
Address: FF24H After reset: FFH R/W
Symbol
7 6 5 4 3 2 1 0
PM4 1 1 1 1 1
PM42
PM41
PM40
PM4n
P4n pin I/O mode selection (n = 0 to 2)
0
Output mode (output buffer on)
1
Input mode (output buffer off)
11.4 Operations of Clock Output Controller
11.4.1 Operation as clock output
The clock pulse is output as the following procedure.
<1> Select the clock pulse output frequency with bits 0 to 3 (CCS0 to CCS3) of the clock output selection register
(CKS) (clock pulse output in disabled status).
<2> Set bit 4 (CLOE) of CKS to 1 to enable clock output.
Remark
The clock output controller is designed not to output pulses with a small width during output
enable/disable switching of the clock output. As shown in Figure 11-4, be sure to start output from the
low period of the clock (marked with * in the figure). When stopping output, do so after the high-level
period of the clock.
Figure 11-4. Remote Control Output Application Example
CLOE
Clock output
*
*