em78f644nso28s ELAN Microelectronics Corp, em78f644nso28s Datasheet - Page 51

• Manufacturer Part Number: em78f644nso28s
• Description: Flash Series 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.0) 05.05.2010
(This specification is subject to change without further notice)
In Pulse Width Modulation (PWM) Output Mode, counting up is performed using
the internal clock. The contents of TCR3 are compared with the contents of the up-
counter. The F/F is toggled when a match is found. While the counter continues
counting, the F/F is toggled again when the counter overflows, after which the counter
is cleared. The F/F output is inverted and output to /PWM pin. A TC3 interrupt is
generated each time an overflow occurs. TCR3 is configured as a 2-stage shift
register and, during output, will not switch until one output cycle is completed
even if TCR3 is overwritten. Therefore, the output can be changed continuously.
However, only when TC3S is set to “1” will the TCR3 start to shift and allows data to
be loaded into TCR3.
6.1.44 Bank 3 RE TC3D (Timer 3 Data Buffer)
Bits 7 ~ 0 (TC3D7 ~ TC3D0): Data Buffer of 8-bit Timer/Counter 3.
6.1.45 Bank 3 RF (Pull-Down Control Register 1)
Bit 7 (/PD77): Control bit used to enable pull-down on P77 pin
Bit 6 (/PD76): Control bit used to enable pull-down of the P76 pin.
Bit 5 (/PD75): Control bit used to enable pull-down of the P75 pin.
Bit 4 (/PD74): Control bit used to enable pull-down of the P74 pin.
Bit 3 (/PD73): Control bit used to enable pull-down of the P73 pin.
Bit 2 (/PD72): Control bit used to enable pull-down of the P72 pin.
Clock Source
TC3 interrupt
TC3D7
/PD77
Up-counter
Bit 7
Bit 7
/PWM
TCR3
F/F
TC3D6
/PD76
Bit 6
Bit 6
0: Enable internal pull-down
1: Disable internal pull-down
0
n/n
1
match
TC3D5
/PD75
n-1
Bit 5
Bit 5
Figure 6-5c PWM Mode Timing Chart
n
n+1
n+2
EM78F648/644/642/641/548/544/542/541N
TC3D4
/PD74
overflow
Bit 4
Bit 4
FE FF
overwrite
0
TC3D3
/PD73
Bit 3
Bit 3
n-1 n
n/m
match
1 period
n+1
TC3D2
/PD72
Bit 2
Bit 2
n+2
overflow
8-Bit Microcontroller
FE FF
TC3D1
Bit 1
Bit 1
”1”
0
Shift
m/m
1
TC3D0
m-1
Bit 0
Bit 0
”1”
m
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