SN8P2624
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 82
Version 0.3
8.4 PWM1
MODE
8.4.1 OVERVIEW
PWM function is generated by TC1 timer counter and output the PWM signal to PWM1OUT pin (P5.3). The 8-bit
counter counts modulus 256, 64, 32, 16 controlled by ALOAD1, TC1OUT bits. The value of the 8-bit counter (TC1C) is
compared to the contents of the reference register (TC1R). When the reference register value (TC1R) is equal to the
counter value (TC1C), the PWM output goes low. When the counter reaches zero, the PWM output is forced high. The
low-to-high ratio (duty) of the PWM1 output is TC1R/256, 64, 32, 16.
PWM output can be held at low level by continuously loading the reference register with 00H. Under PWM operating, to
change the PWM’s duty cycle is to modify the TC1R.
Note: TC1 is double buffer design. Modifying TC1R to change PWM duty by program, there is no glitch
and error duty signal in PWM output waveform. Users can change TC1R any time, and the new reload
value is loaded to TC1R buffer at TC1 overflow.
ALOAD1 TC1OUT PWM duty range TC1C valid value TC1R valid bits value
MAX. PWM
Frequency
(Fcpu = 4MHz)
Remark
0 0
0/256~255/256
0x00~0xFF 0x00~0xFF 7.8125K
Overflow per 256 count
0 1 0/64~63/64 0x00~0x3F 0x00~0x3F
31.25K
Overflow per 64 count
1 0 0/32~31/32 0x00~0x1F 0x00~0x1F
62.5K
Overflow per 32 count
1 1 0/16~15/16 0x00~0x0F 0x00~0x0F
125K
Overflow per 16 count
The Output duty of PWM is with different TC1R. Duty range is from 0/256~255/256.
TC1 Clock
TC1R=00H
TC1R=01H
TC1R=80H
TC1R=FFH
0
1
128
254
255
……
……
0
1
128
254
255
……
……
Low
Low
Low
High
High
Low
High