HMS87C5216 ETC1 [List of Unclassifed Manufacturers], HMS87C5216 Datasheet - Page 73

• Manufacturer Part Number: HMS87C5216
• Description: CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD
• Manufacturer: ETC1 [List of Unclassifed Manufacturers]

19. ANALOG TO DIGITAL CONVERTER
The analog-to-digital converter (A/D) allows conversion of an
analog input signal to a corresponding 8-bit digital value. The A/
D module has eight analog inputs, which are multiplexed into one
sample and hold. The output of the sample and hold is the input
into the converter, which generates the result via successive ap-
proximation.
The analog reference voltage is V
registers which are the control register ADMR and A/D result
register ADDR. The ADMR register, shown in Figure 19-2, con-
trols the operation of the A/D converter module. The port pins
can be configure as analog inputs or digital I/O.
To use analog inputs, each port is assigned analog input port by
setting the bit ANSEL[7:0] in RAFUNC register. And selected
SEP. 2004 Ver 1.01
R1[7]/AN3
R1[6]/AN2
R1[5]/AN1
R1[4]/AN0
AVDD
ADEN
ADEN
ADEN
ADEN
ADEN
DD
. The A/D module has two
ADAN[1:0]
Figure 19-1 A/D Converter Block Diagram
00
11
10
01
Sample & Hold
S/H
Resistor
Ladder
Circuit
the corresponding channel to be converted by setting ADS[2:0].
The processing of conversion is start when the start bit ADST is
set to “1”. After one cycle, it is cleared by hardware. The register
ADCR contains the results of the A/D conversion. When the con-
version is completed, the result is loaded into the ADCR, the A/
D conversion status bit ADSF is set to “1”, and the A/D interrupt
flag ADIF is set. The block diagram of the A/D module is shown
in Figure 19-1. The A/D status bit ADSF is set automatically
when A/D conversion is completed, cleared when A/D conver-
sion is in process. The conversion time takes maximum 30 uS (at
fxin=4 MHz).
A/D Result Register
Approximation
ADDR(8-bit)
Successive
Circuit
ADDRESS : EDH
RESET VALUE : Undefined
ADIF
HMS87C5216
A/D Interrupt