8-Bit Timers(Tmra) - Toshiba TMP91C824F Data Book

3.7 8-bit Timers (TMRA)
The TMP91C824 features 4 channel(TMRA0 to TMRA3) built-in 8-bit timers.
These timers are paired into 2 modules: TMRA01 and TMRA23. Each module consists of 2 channels and can
operate in any of the following 4 operating modes.
•
8-Bit Interval Timer Mode
•
16-Bit Interval Timer Mode
•
8-Bit Programmable Square Wave Pulse Generation Output Mode (PPG: variable duty cycle with
variable period)
•
8-Bit Pulse Width Modulation Output Mode (PWM – variable duty cycle with constant period)
Figure 3.7.1 to Figure 3.7.2 Show block diagrams for TMRA01 and TMRA23.
Each channel consists of an 8-bit up counter, an 8-bit comparator and an 8-bit timer register. In addition, a
timer flip-flop and a prescaler are provided for each pair of channels.
The operation mode and timer flip-flop condition are controlled by 5bytes registers.
We call control registers SFRs: Special Function Registers.
Each of the two modules (TMRA01 and TMRA23) can be operated independently. All modules operate in the
same manner; hence only the operation of TMRA01 is explained here.
The contents of this chapter are as follows.
3.7.1 Block diagrams
3.7.2 Operation of each circuit
3.7.3 SFRs
3.7.4 Operation in each mode
(1) 8-Bit Timer Mode
(2) 16-Bit Timer Mode
(3) 8-Bit PPG (programmable pulse generation) Output Mode
(4) 8-Bit PWM (pulse width modulation) Output Mode
(5) Mode settings
External
pin
SFR
(address)
Table 3.7.1 Registers and pins for each module
Module
TMRA01
Input pin for external
clock (shared with PB0)
Output pin for timer
flip-flop (shared with PB1)
Timer run register TA01RUN (0100H)
TA0REG (0102H)
Timer register
TA1REG (0103H)
Timer mode register TA01MOD (0104H)
Timer flip-flop control
TA1FFCR (0105H)
register
91C824-88
TMRA23
TA0IN
None
TA1OUT TA3OUT
(shared with PB2)
TA23RUN (0108H)
TA2REG (010AH)
TA3REG (010BH)
TA23MOD (010CH)
TA3FFCR (010DH)
TMP91C824