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Start ý CreataLink Hardware ý FLEX Stack Firmware ý Selecting a Microcontroller ý Putting it All Together ý Sources and PDF

SELECTING A MICROCONTROLLER

The FLEX Stack has been ported to Toshibaýs TLCS-900 and TLCS-870 series of microcontrollers. There are several dozen members to choose from between these two processor families. However, the requirements of the FLEX Stack driver, the CreataLink hardware interface, and your application requirements combined will reduce the number of processor options. The FLEX Stack driver requires about 500 bytes of SRAM, eliminating the processors in the TLCS-780 family that have only 256 bytes of SRAM. Unless youýre sure that your application can get by with only a few bytes of SRAM, it also eliminates those processors with 512 bytes of SRAM.

The FLEX Stack also requires about 12 KB of ROM (EPROM or flash memory), so you need a processor with at least 16 KB, but more likely 24 KB or 32 KB of ROM. Also, a hardware SPI port is required by the FLEX Stack to interface with the CreataLink receiver.

If you wish to generate the CreataLinkýs 76.8-kHz clock from the microcontrollerýs master clock, you need to select a processor with a programmable pulse generator or PWM output from its internal counters. By using a standard 7.3728-MHz crystal and having the counter divide by 96, you can generate a 50% duty cycle, 76.8-kHz clock for the CreataLink receiver to use. (The 7.3728-MHz crystal also works nicely for producing exact data transfer rates for a UART.)

Your application will add some additional requirements for the processor. If, for example, you want a UART to communicate with an X10 transceiver, youýll need to select a processor with both a UART and an available counter for data transfer rate generation. After all things are considered, your choices will be reduced to a more easily manageable number.

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