Grantronics: GMC75X Credit Card Microcontroller

Contents:

• Product Summary
• Key Features
• CPU Selection
• Prices

Product Summary

Power I2C programming and/or expansion				Optional I/O connector and proto area
		GMC75X Microcontroller (Atmel AT89C2051 version)
		Ideal for those small jobs where a standard embedded controller can't be justified.

The GMC75X is like a "BASIC Stamp" except that you can program the module in 'C' using C-FLEA and a download cable. Alternatively, use 8051 assembler (you will need a programmer for the CPU though!).

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Key Features

• Small: Same size as a credit card (54mm x 85mm or 2.125" x 3.35").
• Flexible: Uses any one of the following processors: Philips 87C748/749/750/751/752 or the Atmel 89C1051 or 89C2051. You pick the CPU that best suits your application.
• Expandable: Provides an external I²C I/O expansion and programming bus, most CPU pins are available on a header and there is a small prototyping area (nearly 2 sq inches).
• Software: You can use the Dunfield MICRO-C compiler and cross assembler to write native 8051 code. Or use the Dunfield C-FLEA Virtual Machine (requires a CPU with 2k program memory) with the compiled code downloaded into the onboard EEPROM (use our PC2I2C interface) - great for educational situations!
• Easy to Power: A simple unregulated 8-15Vdc supply is required.
• Reliable: A MAX1232 is provided to recover gracefully from brownouts.

Note: You can't program any of the CPUs in the GMC75X - you can only download to the on-board EEPROM. 

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CPU Selection

For speed, use the 87C750 (available up to 40MHz). 11.0592MHz is standard.

For analogue I/O, use the 87C752 or 87C749 (5 x 8-bit A/D + PWM) or the 89C2051 (analogue comparator).

For I²C slaves, use the 87C751 or 87C752.

For a hardware UART, use the 89C2051.

For quick re-programming, use the 89C2051 with 2k of Flash program memory.

For more RAM, use the 89C2051 with 128 bytes (the others only have 64 bytes).

For most I/O, use the 87C749 or 87C752 (2 x 8-bit ports + 1 x 5-bit port).

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Prices

• All orders exported from Australia are exempt GST.
• All prices except where noted are in Australian Dollars.
• Prices are for single units. Please ask for quantity discounts.
• Shipping costs are extra.
• Prices may be changed at any time due to various factors including exchange rates.

Application Example

Just before Christmas 1997, our two daughters asked why we didn't have flashing Christmas tree lights? So later, while the girls were out shopping, I asked my son to wire up a few LEDs while I wrote some software for a GMC75X (89C2051). When the girls saw the tree, they thought it was great! For Christmas 1998, we have been more adventurous and used a few more LEDs in the shape of a Christmas Star for a more spectacular result! Christmas 1999 saw the Christmas Tree released as a kit.

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Last updated: 18 Jan 2008

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