80C32 Module

_________________General Description

The Maxim 80C32 microcontroller (µC) module is

intended for use with this and other Maxim evaluation

kits (EV kits). It contains the 80C32 µC, RS-232 inter-

face, 8kbytes of EPROM, 32kbytes of static RAM, and

address decoding logic. A 40-pin connector mates

with a connector found on Maxim EV kits designed to

interface with the 80C32 module.

The module is connected to an IBM-compatible

personal computer over a serial communications port.

Software provided with each EV kit runs on the

computer and controls the unit consisting of the 80C32

module and EV kit. The program uses a routine stored

in the 27C64 EPROM to download special 80C32 code

for each kit. The downloaded code controls the EV kit

and, together with the program running on the person-

al computer, displays the output data.

The board operates from a single 8V to 22V supply.

Both the pre-regulated and regulated +5V levels are

available to the EV kit through the 40-pin connector.

80C32 Module Power Supply

The Maxim 80C32 module requires an input of 8V to 22V

for normal operation. An on-board 78M05 power regula-

tor supplies the 5V required for the logic on the module,

and any 5V requirements for the EV kit attached to the

40-pin connector. The pre-regulated voltage is also

available on the data connector. The source must be

capable of supplying 100mA for the module and meet-

ing the load requirements of the EV kit.

Microprocessor Supervisor

A MAX707 on the module monitors the 5V logic supply,

generates the power-on reset, and produces a reset

pulse whenever the reset button is pressed. A watch-

dog function was not included because they frequently

interfere while debugging programs, and debugging is

a prime function of this board.

80C32 Microcontroller

The 80C32 is a member of the popular Intel 8051 family

of µCs. It is a low-power CMOS version that requires

external ROM for program storage, 256 bytes of inter-

nal RAM, and four 8-bit I/O ports. Three of the ports are

required by the system for serial communications and

memory control. The fourth port (P1) is available

through the data connector.

The 80C32 communicates with the PC over a serial

RS-232 link. A MAX233 acts as a level shifter between

the ±15V RS-232 signals and the TTL levels of the

80C32. The MAX233 also generates the output

voltages necessary to drive RS-232 lines.

Port 0 (pins 32–39) of the 80C32 multiplexes the lower

eight bits of memory address and the eight bits of

read/write data. The lower eight bits of address data

are latched during each I/O cycle by the 74HCT573

octal latch. The latch is controlled by the address latch

enable (ALE) signal of the 80C32. Port 2 (pins 21–28) of

the 80C32 supplies the upper eight bits of address

information.

MAX110 Evaluation System/Evaluation Kit

______________________________________________________________________________________

13

____80C32 Module Component List

DESIGNATION

QTY

DESCRIPTION

C1, C2

2

15pF ceramic capacitors

C4, C5, C6, C7,

C8, C9, C10,

C11, C12

9

0.1µF, 50V ceramic capacitors

C3, C13, C14

3

22µF, 16V radial electrolytic

capacitors

D1

1

1N4001 diode

J1

1

40-pin right-angle male connector

J2

1

DB9 right-angle socket

R1

1

620

Ω resistor

RS1

1

10k

Ω, 10-pin, 9-resistor SIP

SW1

1

Power switch

SW2

1

Reset switch

IC1

1

80C32

IC2

1

MAX233CPP

IC3

1

27C64

IC4

1

74HCT573

IC5

1

74HCT139

IC6

1

74HCT08

IC7

1

74HCT245

IC8

1

62256

IC9

1

78M05

IC10

1

MAX707CPA

Y1

1

11.059MHz crystal

None

1

2-pin power connector

None

1

28-pin 600-mil socket for IC3

(the EPROM)

None

4

Rubber feet

None

1

3.00" x 5.50" PC board