DS87C550 Datasheet, PDF (6/50 Pages) Dallas Semiconductor – EPROM High-Speed Micro with A/D and PWM

PLCC/
CLCC
1,
62-68
QFP
64-71
SIGNAL NAME
P5.0-P5.7
DS87C550
DESCRIPTION
Port 5 - I/O. Port 5 functions as an open-drain 8-bit bi-directional I/O port or
alternately as an interface to the A/D converter. When used for general purpose
I/O, these pins operate in a quasi-bi-directional mode. Writing a logic 1 to these
pins (reset condition) will cause them to tri-state. This allows the pins to serve as
inputs since the tri-state condition can be driven by an external device. If a logic 0
is written to a pin, it is pulled down internally and therefore serves as an output
pin containing a logic 0. Because these pins are open-drain, external pullup
resistors are required to create a logic 1 level when they are used as outputs. As
an alternate function Port 5 pins operate as the analog inputs for the A/D
converter as described below.
1
68
67
66
65
64
63
62
3-6, 32
33, 38
71
70
69
68
67
66
65
64
28, 29
37
74-77
P6.0-P6.5
P6.7
Port Alternate Mode
P5.0 ADC0 Analog to Digital Converter input channel 0
P5.1 ADC1 Analog to Digital Converter input channel 1
P5.2 ADC2 Analog to Digital Converter input channel 2
P5.3 ADC3 Analog to Digital Converter input channel 3
P5.4 ADC4 Analog to Digital Converter input channel 4
P5.5 ADC5 Analog to Digital Converter input channel 5
P5.6 ADC6 Analog to Digital Converter input channel 6
P5.7 ADC7 Analog to Digital Converter input channel 7
Port 6 - I/O. Port 6 functions as an 6-bit bi-directional I/O port or alternately as
an interface to the PWM and A/D on-board peripherals. As an I/O port, these pins
operate as described in Port 1. The alternate modes of Port 6 are detailed below.
4
75
5
76
32
28
33
29
6
77
38
37
3
74
59
60
58
59
61
63
60
61
3, 21
22, 30
33, 36
43, 44
62, 73
78, 79
A_vref+
A_vref-
A_VCC
A_VSS
NC
Port Alternate Function
P6.0 PWMO0 PWM channel 0 output
P6.1 PWMO1 PWM channel 1 output
P6.2 PWMO2 PWM channel 2 output
P6.3 PWMO3 PWM channel 3 output
P6.4 PWMC0 PWM0 clock input
P6.5 PWMC1 PWM1 clock input
P6.7 STADC External A/D conversion start signal (active low)
A/D +Reference - Input. When selected, supplies the positive reference voltage
for the A/D converter. This signal should be isolated from digital V_CC to prevent
noise from affecting A/D measurements.
A/D -Reference - Input. When selected, supplies the negative reference voltage
for the A/D converter. This signal should be isolated from digital GND to prevent
noise from affecting A/D measurements.
Analog V_CC
Analog Ground
NC-Reserved. These pins should not be connected. They are reserved for use
with future devices in this family.
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