Microcontroller; Microcontroller Features; Rs-232 Interface; Internal Time Base Generation - ST EVALCOMMBOARD Manual

Microcontroller

3 Microcontroller
3.1

Microcontroller features

The board is based on the ST72F651AR6 USB microcontroller, its mains features are:
●
Up to 8MHz ST7 control unit
●
32 KBytes embedded Flash program memory
●
5 KBytes embedded RAM memory
●
UVLO
●
Up to 47 general purpose IOs with 3 Interrupt sources, two separated IO banks (one
supplied at 5V and one between 2.7V and 5V).
This microcontroller embeds several on-chip peripherals:
●
Programmable watchdog timer/counter
●
Programmable DMA controller (DTC) with 256 bytes dedicated memory
●
Full-speed USB controller with 5 endpoints and a 1280 bytes dedicated memory for
buffers
● One 16-bit timer with 2 Output Compare units
●
A 10-bit PWM generator with 2 channels
●
A full-duplex SPI peripheral (master / slave)
●
I²C bus interface (single master)
●
8-channels, 8-bit A/D Converter
3.2

RS-232 Interface

The RS-232 interface is emulated by software using:
●
One general purpose IO () as TxD signal
●
One Interrupt source IO () as RxD signal.
●
One Output compare unit to generate the correct timing for transmission and reception.
The firmware implements a half-duplex RS-232 interface, whenever a simultaneous
reading/writing operation occurs the writing operation is aborted and the reading operation
is performed without loss of data.
3.3

Internal time base generation

An internal 1ms time base is generated using one output compare resource and a free
counter. The free counter is then used to generate up to 10 programmable timeout counters
(with 1ms resolution).
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