w83l950d Winbond Electronics Corp America, w83l950d Datasheet - Page 73

• Manufacturer Part Number: w83l950d
• Description: Peripheral Personal Computer Keyboard Controller
• Manufacturer: Winbond Electronics Corp America

16.2 A/D conversion register 0(AD0)
16.3 A/D conversion register 1(AD1)
16.4 D-A Converter
The keyboard controller has two internal D-A converters (DA1 and DA0) with 8-bit resolution. The result
of D-A conversion is output from the DA1 or DA0 pin by setting the DA output enable bit to "1".
When using the D-A converter, the corresponding port direction register bit (P56/DA0/PWM01 or
P57/DA1/PWM11) must be set to '0" (input state). The output analog voltage V is determined by the
value n (decimal notation) in the D-A conversion register as follows,
At reset, the D-A conversion registers are cleared to "00h", the DA output enable bits are cleared to "0",
and the P56/DA0/PWM01 and P57/DA1/PWM11 pins become high impedance. The DA output does
not have buffers accordingly, connect an external buffer when driving a low-impedance load.
16.5 D-A Conversion Register 0(DA0)
16.6 D-A Conversion Register 1(DA1)
17. COMPARATOR CIRCUIT
The comparator circuit consists of resistors, comparators, a comparator control circuit, the comparator
reference input selection bit (bit 7 of SIO2CON), a comparator data register (CMPD), the comparator
reference power source input pin (P00/ P3REF) and analog signal input pins (P3o-P37) The analog
input pin (P30-P37) also functions as an ordinary digital port
17.1 Comparator Operation
V - VREF X n/256 (n - 0 to 255), where VREF is the reference voltage.
remains at “0" during an A-D conversion, and changes to "1" when an A-D conversion end.
Writing '0" to this bit starts the A-D conversion.
SFR address
Default value
SFR address
Default value.
SFR address
Default value
SFR address
Default value
To activate the comparator, first set port P3 to input mode by set- ting the corresponding
direction register (P3D to "0" to use port P3 as an analog voltage input pin. The internal fixed
analog voltage (Voc x 29/32) can be generated by setting "1" to the comparator reference input
0xE3
0x00
0xE4
0x00
0xE5
0x00
0xE6
0x00
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W83L950D