EVAL-ADUC842QSZ Analog Devices Inc, EVAL-ADUC842QSZ Datasheet - Page 42

• Manufacturer Part Number: EVAL-ADUC842QSZ
• Description: Analog MCU Evaluation Board
• Manufacturer: Analog Devices Inc
• Series: QuickStart™ Kitr
• Type: MCUr

Specifications of EVAL-ADUC842QSZ

• Silicon Manufacturer: Analog Devices
• Core Architecture: 8052
• Silicon Core Number: ADuC842
• Tool / Board Applications: General Purpose MCU, MPU, DSP, DSC
• Mcu Supported Families: ADUC8xx
• Contents: Evaluation Board, Power Supply, Cable, Software and Documentation
• Development Tool Type: Hardware - Eval/Demo Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ADuC824
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

ADuC841/ADuC842/ADuC843
PULSE-WIDTH MODULATOR (PWM)
The PWM on the ADuC841/ADuC842/ADuC843 is a highly
flexible PWM offering programmable resolution and an input
clock, and can be configured for any one of six different modes
of operation. Two of these modes allow the PWM to be config-
ured as a ∑-∆ DAC with up to 16 bits of resolution. A block
diagram of the PWM is shown in Figure 47. Note the PWM
clock’s sources are different for the ADuC841, and are given in
Table 17.
The PWM uses five SFRs: the control SFR (PWMCON) and
four data SFRs (PWM0H, PWM0L, PWM1H, and PWM1L).
Table 17. PWMCON SFR Bit Designations
Bit No.
7
6
5
4
3
2
1
0
TO/EXTERNAL PWM CLOCK
Name
SNGL
MD2
MD1
MD0
CDIV1
CDIV0
CSEL1
CSEL0
f
XTAL
f
f
XTAL
VCO
Figure 47. PWM Block Diagram
/15
Description
Turns off PMW output at P2.6 or P3.4, leaving the port pin free for digital I/O.
PWM Mode Bits.
The MD2/1/0 bits choose the PWM mode as follows:
MD2
0
0
0
0
1
1
1
1
PWM Clock Divider.
Scale the clock source for the PWM counter as follows:
CDIV1
0
0
1
1
PWM Clock Divider.
Select the clock source for the PWM as follows:
CSEL1
0
0
1
1
SELECT
CLOCK
MODE
MD1
0
0
1
1
0
0
1
1
CDIV0
0
1
0
1
CSEL0
0
1
0
1
16-BIT PWM COUNTER
PROGRAMMABLE
COMPARE
PWM0H/L
DIVIDER
MD0
0
1
0
1
0
1
0
1
Description
PWM Counter = Selected Clock/1
PWM Counter = Selected Clock/4
PWM Counter = Selected Clock/16
PWM Counter = Selected Clock/64
Description
PWM Clock = f
PWM Clock = f
PWM Clock = External input at P3.4/T0
PWM Clock = f
PWM1H/L
Mode
Mode 0: PWM Disabled
Mode 1: Single variable resolution PWM on P2.7 or P3.3
Mode 2: Twin 8-bit PWM
Mode 3: Twin 16-bit PWM
Mode 4: Dual NRZ 16-bit
Mode 5: Dual 8-bit PWM
Mode 6: Dual RZ 16-bit
Reserved
P2.6
P2.7
Rev. 0 | Page 42 of 88
XTAL
XTAL
VCO
/15, ADuC841 = f
, ADuC841 = f
= 16.777216 MHz, ADuC841 = f
PWMCON, as described in the following sections, controls the
different modes of operation of the PWM as well as the PWM
clock frequency.
PWM0H/L and PWM1H/L are the data registers that deter-
mine the duty cycles of the PWM outputs. The output pins that
the PWM uses are determined by the CFG841/CFG842 register,
and can be either P2.6 and P2.7 or P3.4 and P3.3. In this section
of the data sheet, it is assumed that P2.6 and P2.7 are selected as
the PWM outputs.
To use the PWM user software, first write to PWMCON to
select the PWM mode of operation and the PWM input clock.
Writing to PWMCON also resets the PWM counter. In any of
the 16-bit modes of operation (Modes 1, 3, 4, 6), user software
should write to the PWM0L or PWM1L SFRs first. This value is
written to a hidden SFR. Writing to the PWM0H or PWM1H
SFRs updates both the PWMxH and the PWMxL SFRs but does
not change the outputs until the end of the PWM cycle in
progress. The values written to these 16-bit registers are then
used in the next PWM cycle.
PWMCON PWM
SFR Address
Power-On Default
Bit Addressable
OCS
/DIVIDE FACTOR (see the CFG841 register)
∑
OCS
-∆ DAC
∑
-∆ DAC
/DIVIDE FACTOR /15 (see the CFG841 register)
OSC
Control SFR
AEH
00H
No