µ
PD75512
25
6.7 TIMER/PULSE GENERATOR
The
µ
PD75512 contains a timer/pulse generator, that can be used as the timer or the pulse generator. Timer/pulse
generator has the following functions.
(a)
Function, when used in the timer mode
• 8-bit interval timer operation (IRQTPG generation), for which the clock source can be changed in 5
steps.
• Square waveform output to the PPO pin
(b)
Function, when used in the PWM pulse generation mode
• 14-bit accuracy PWM pulse output to PPO pin (can be used as a D/A converter for electronics tuning).
• Fixed time interval interrupt generation (2
15
/f
X
= 7.81ms: f
X
= 4.19 MHz)
When no pulse output is required, the PPO pin can be used as 1-bit output port.
Note:
When setting the STOP mode, if the timer pulse generator is in operating mode, erroneous operation
may occur. Therefore, the timer/pulse generator must be set in no-operation state by the mode
register, before setting the STOP mode.
Internal bus
8
8
TPGM3
(Set to 1 )
MODH
Modulo register L (8)
Modulo register H (8)
Frequency
divider
f
x
1/2
TPGM1
Prescaler select latch (5)
Clear
CP
Clear
8
Count register (8)
Comparator (8)
T F/F
Set
Coincidence
Modulo latch H (8)
8
TPGM4 TPGM5 TPGM7
PPO
Output buffer
INTTPG
(IRQTPG
set signal)
Selector
MODL
Fig. 6-6 Timer/Pulse Generator Block Diagram (Timer Mode)