Chapter 12 Timer/Counter
12-3
12.3 Detailed Explanation
12.3.1 Overview
The TX4937 has an on-chip 3-channel 32-bit timer/counter. Each channel supports the following
modes.
(1) Interval Timer Mode (Timer 0, 1, 2)
This mode periodically generates interrupts.
(2) Pulse Generator Mode (Timer 0, 1)
This is the pulse signal output mode.
(3) Watchdog Timer Mode (Timer 2)
This mode is used to monitor system abnormalities.
12.3.2 Counter
Clock
The clock used for counting can be set to a frequency that is 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, or
1/256 of the internal clock (IMBUSCLK) frequency, or can be selected from nine counter input signal
(TCLK) types. Divide Register
n
(TMCCDRn) and the Counter Clock Select bit (TMTCRn.CCS) are
used to select the counter clock. In this situation, IMBUSCLK is the internal clock signal which is the
G-Bus clock divided by 2. See “Chapter 6 Clocks” for more information.
The counter input signal (TCLK) is used by three channels. Using TCLK makes it possible to count
external events. The External Clock Edge bit (TMTCRn.ECES) can be used to select the clock
rising/falling count.
Set the TCLK clock frequency to 45% or less of IMBUSCLK (TCLK = 27 MHz or less when
IMBUSCLK = 60 MHz). The following tables shows example count times when using 60 MHz or 66
MHz IMBUSCLK.
Table 12.3.1 Divide Value and Count (IMBUSCLK = 60 MHz)
Divide
Rate
TMCCDRn.
CCD
Counter Clock
Frequency (Hz)
Resolution (ns)
Max. Set Time
(sec.)
TMCPRAn Value
for 1 sec.
2
4
8
16
32
64
128
256
000
001
010
011
100
101
110
111
30.0 M
15.0 M
7.5 M
3.75 M
1.9 M
937.5 K
468.8 K
234.4 K
33.33
66.67
133.33
266.67
533.33
1066.67
2133.33
4266.67
143.17
286.33
572.66
1145.32
2290.65
4581.30
9162.60
18325.20
30000000
15000000
7500000
3750000
1875000
937500
468750
234375
Summary of Contents for TX49 TMPR4937
Page 1: ...64 Bit TX System RISC TX49 Family TMPR4937 Rev 2 0 ...
Page 4: ......
Page 13: ...Table of Contents ix TMPR4937 Revision History 1 ...
Page 14: ...Table of Contents x ...
Page 15: ...Handling Precautions ...
Page 16: ......
Page 18: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 40: ...3 General Safety Precautions and Usage Considerations 3 18 ...
Page 42: ...4 Precautions and Usage Considerations 4 2 ...
Page 43: ...TMPR4937 2005 3 Rev 2 0 ...
Page 44: ......
Page 52: ...Chapter 1 Overview and Features 1 6 ...
Page 156: ...Chapter 7 External Bus Controller 7 56 ...
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Page 506: ...Chapter 20 Extended EJTAG Interface 20 8 ...
Page 530: ...Chapter 22 Pinout and Package Information 22 10 ...
Page 542: ...Chapter 24 Parts Number when Ordering 24 2 ...