
CHAPTER 8 8-BIT TIMER/EVENT COUNTERS 50 AND 51
User’s Manual U17260EJ6V0UD
254
8.3 Registers Controlling 8-Bit Timer/Event Counters 50 and 51
The following four registers are used to control 8-bit timer/event counters 50 and 51.
Timer clock selection register 5n (TCL5n)
8-bit timer mode control register 5n (TMC5n)
Port mode register 1 (PM1) or port mode register 3 (PM3)
Port register 1 (P1) or port register 3 (P3)
(1) Timer clock selection register 5n (TCL5n)
This register sets the count clock of 8-bit timer/event counter 5n and the valid edge of the TI5n pin input.
TCL5n can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears TCL5n to 00H.
Remark
n = 0, 1
Figure 8-5. Format of Timer Clock Selection Register 50 (TCL50)
Address: FF6AH
After reset: 00H
R/W
Symbol
7
6
5
4
3
2
1
0
TCL50
0
TCL502
TCL501
TCL500
Count clock selection
Note 1
TCL502
TCL501
TCL500
fPRS =
2 MHz
fPRS =
5 MHz
fPRS =
10 MHz
fPRS =
20 MHz
0
TI50 pin falling edge
0
1
TI50 pin rising edge
0
1
0
fPRS
Note 2
2 MHz
5 MHz
10 MHz
20 MHz
0
1
fPRS/2
1 MHz
2.5 MHz
5 MHz
10 MHz
1
0
fPRS/2
2
500 kHz
1.25 MHz
2.5 MHz
5 MHz
1
0
1
fPRS/2
6
31.25 kHz
78.13 kHz
156.25 kHz
312.5 kHz
1
0
fPRS/2
8
7.81 kHz
19.53 kHz
39.06 kHz
78.13 kHz
1
fPRS/2
13
0.24 kHz
0.61 kHz
1.22 kHz
2.44 kHz
Notes 1.
If the peripheral hardware clock (fPRS) operates on the high-speed system clock (fXH) (XSEL = 1), the
fPRS operating frequency varies depending on the supply voltage.
VDD = 4.0 to 5.5 V: fPRS ≤ 20 MHz
VDD = 2.7 to 4.0 V: fPRS ≤ 10 MHz
VDD = 1.8 to 2.7 V: fPRS ≤ 5 MHz (Standard and (A) grade products only)
2.
If the peripheral hardware clock (fPRS) operates on the internal high-speed oscillation clock (fRH) (XSEL
= 0), when 1.8 V
≤ VDD < 2.7 V, the setting of TCL502, TCL501, TCL500 = 0, 1, 0 (count clock: fPRS) is
prohibited.
Cautions 1. When rewriting TCL50 to other data, stop the timer operation beforehand.
2. Be sure to clear bits 3 to 7 to “0”.
Remark
fPRS: Peripheral hardware clock frequency
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