The port 3 pins (10–17) provide several unrelated

functions. Pins 10 and 11 are used as the receive data

(RxD) and transmit data (TxD) pins of the RS-232 link.

Pins 16 and 17 act as the write (WR) and read (RD)

control signals for the data I/O cycles. Four other pins

are configured as interrupt and timer controls, but are

not used on this board.

Memory

The board has a 27C64 EPROM containing code for

initializing the 80C32 and downloading additional

program code to the 62256 RAM. After a reset, the

EPROM resident code initializes the 80C32, determines

the address range of the RAM, sets the RS-232 baud

rate to 1200, and waits for communications from the

PC. Receiving any character will prompt the program to

send an initial banner that includes the program name,

revision level, and boundaries of the on-board RAM.

The 62256 CMOS (32kbyte) static RAM is used to hold

program code for the various Maxim EV kits that use

the 80C32 module as the controller. Programs are

transferred from disk to the RAM using software run-

ning on a personal computer, such as MAXLOAD or

other programs provided with Maxim EV kits. Programs

written to execute from this RAM start at 4000 (HEX)

and are typically less than 4kbytes long. The remaining

RAM is available for data storage.

Address Ranges

Logic on the module board generates various enable

signals for different address ranges. The ROM and

RAM enable signals are fed directly to the respective

chips. Several additional signals (CS0–CS3) are

available on the data connector to be used by Maxim

EV kits. Table 11 outlines the address range for each of

the elements found on the 80C32 module.

Data I/O Connector

A 40-pin connector mounted on the edge of the printed

circuit board provides connection between the µC

module and other Maxim EV kits. Both power and digi-

tal signals are transferred via the connector. To join the

module board with an EV kit, carefully align and insert

the pins on the connector with the mating 40-pin

female connector of the kit. The pin functions are listed

in Table 12.

Software Architecture

Software for EV kits using the Maxim 80C32 module is

divided into three elements: the interface program run-

ning on an IBM-compatible PC, a module program

located in EPROM, and a program supplied on disk

that is transferred to the RAM located on the module.

EPROM Resident Program

The EPROM resident program initializes the 80C32,

establishes communications over the RS-232 link, veri-

fies the static RAM, and downloads other programs. Its

operation starts on power-up and whenever the reset

button is pressed. After reset, the program waits indefi-

nitely to receive a character over the RS-232 port. When

the first character is received, a logon banner identifying

the module and firmware revision is transmitted.

MAX110 Evaluation System/Evaluation Kit

14

______________________________________________________________________________________

ADDRESS RANGE (HEX)

ENABLE SIGNAL

0000

➔ 3FFF

ROM

4000

➔ BFFF

RAM

C000

➔ CFFF

CS0

D000

➔ DFFF

CS1

E000

➔ EFFF

CS2

F000

➔ FFFF

CS3

PIN

FUNCTION

DESCRIPTION

1–4

Ground

5, 6

Pre-regulator input

7, 8

Regulated +5V

9

RD

Read strobe

10

WR

Write strobe

11

CS0

Address C000–CFFF

12

CS1

Address D000–DFFF

13

CS2

Address E000–EFFF

14

CS3

Address F000–FFFF

15–18

ADDR0–ADDR3

Lowest 4 bits of address

19–26

DB0–DB7

8-bit data bus

27–34

P1.0–P1.7

8 bits of port 1

35–40

Reserved

Table 11. Address Ranges in Hexadecimal

Table 12. I/O Connector Pin Functions