Counter; Interval Timer Mode - Toshiba TX49 TMPR4937 Manual

Table 12.3.2 Divide Value and Count (IMBUSCLK = 66 MHz)
Divide TMCCDRn.
Rate CCD
2 000
4 001
8 010
16 011
32 100
64 101
128 110
256 111
12.3.3

Counter

Each channel has an independent 32-bit counter. Set the Timer Count Enable bit (TMTCRn.TCE) and
the 32-bit counter will start counting.
Clear the Timer Count Enable bit to stop the counter. If the Counter Reset Enable bit
(TMTCRn.CRE) is set, then the counter will be cleared also. The Watchdog Timer Disable bit
(TMWTRM2.WDIS) must be set in order to stop and clear this counter when in the Watch Dog Timer
mode.
Also, reading the Timer Read Register (TMTRR) makes it possible to fetch the counter value.
12.3.4

Interval Timer Mode

The Interval Timer mode is used to periodically generate interrupts. Setting the Timer Mode field
(TMTCRn.TMODE) of the Timer Control Register to "00" sets the timer to the Interval Timer mode.
This mode can be used by all timers.
When the count value matches the value of Compare Register A (TMCPRAn), the Interval Timer
TMCPRA Status bit (TMTISRn.TIIS) of the Timer Interrupt Status Register is set. When the Interval
Timer Interrupt Enable bit (TMITMRn.TIIE) of the Interval Timer Mode Register is set, timer interrupts
occur. When a "0" is written to the Interval Timer TMCPRA Status bit (TMTISRn.TIIS), TIIS is cleared
and timer interrupts stop.
If the Timer Zero Clear Enable bit (TMITMRn.TZCE) is set, the counter is cleared to 0 if the count
value matches the Compare Register A (TMCPRAn) value. Count operation stops when the Timer Zero
Clear Enable bit (TMITMRn.TZCE) is cleared.
The level of the TIMER[1:0] output signal stays in the initial state (Low) in this mode. Output is
undefined when changing from the Pulse Generator mode to this mode. Figure 12.3.1 shows an outline
of the count operation and generation of interrupts when in the Interval Timer mode and Figure 12.3.2
shows the operation when using an external input clock.
Counter Clock
Resolution (ns)
Frequency (Hz)
33.0 M
16.5 M
8.3 M
4.1 M
2.1 M
1031.3 K
515.6 K 1939.39
257.8 K 3878.79
12-4
Chapter 12 Timer/Counter
Max. Set Time TMCPRAn Value
(sec.)
30.30 130.15
60.61 260.30
121.21 520.60
242.42 1041.20
484.85 2082.41
969.70 4164.82
8329.63
16659.27
for 1 sec.
33000000
16500000
8250000
4125000
2062500
1031250
515625
257813