BiPOM Electronics MINI-MAX/51-C2, Technical Manual, Page: 5 / 12

5
Micro-controller
MINI-MAX/51-C2 has an ATMEL AT89C51ED2 micro-controller (U2). Micro-controller ports and power
lines are provided on a 20-pin expansion bus for interfacing to peripherals and other external circuits.
AT89C51ED2 has 4 ports that are available on the 8051 family of micro-controllers: P0 … P3.
P0 has open collector outputs that are available on the LCD connector with 4.7K pull-up (RB1). P1 and
P2 are general-purpose bi-directional input/output ports. Port 2 is available on the keypad connector.
P1 and P3 are available on the expansion connector. P3 pins can either be used as general-purpose
input/output pins or have special purposes such as asynchronous serial port, interrupt inputs and timer
inputs.
More information on the AT89C51ED2 micro-controller can be obtained from ATMEL web site at
http://www.atmel.com .
Secondary Micro-controller
MINI-MAX/51-C2 has a Microchip PIC16F818 micro-controller to select an In-circuit Programming
mode or Run mode of the main Flash micro-controller. When a Run mode is used, PIC16F818 works
as an I2C slave peripheral device and can provide 5-channel 10-bit ADC using the 4.096V internal or
an external voltage reference source.
In-System Programming
AT89C51ED2 micro-controller can be re-programmed remotely over the RS-232 interface using a
second micro-controller on the board ( PIC16F818 ). The in-circuit programming feature simplifies
program development on the board since downloading programs from a host PC takes only few
seconds. User programs can also be debugged over the serial port.
8051/52, BASCOM51, SDCC development systems based on Micro-IDE Integrated Development
Environment from BiPOM Electronics, fully support In-System Programming and debugging on
the MINI-MAX/51-C2 using the serial port.
The on-chip Downloadable Flash of AT89C51ED2 allows the program memory to be reprogrammed in-
system through RS-232 serial interface.
The board operates in the two modes:
1- RUN mode
2- PROGRAM mode
Run mode is a standard mode when AT89C51ED2 is running its own program.
Program mode is a special mode when
t
he hardware conditions during the reset pulse forces the on-
chip boot loader execution.
PC changes the board mode through the RS-232 serial interface by a using of RTS line.
PIC16F818 is polling this line permanently and if the signal changes the level then PIC16F818
switches the board mode.
EEPROM
MINI-MAX/51-C2 uses a 24C04 (U3) 512 byte Electrically Erasable Programmable Read-Only-Memory
(EEPROM). Typically this EEPROM is used for storing calibration values for sensors, customer
identification, serial number and other parameters. This EEPROM is on a socket and can easily be
replaced with higher capacity EEPROM’s ( up to 128 Kilobytes ).