May 18, 2015

ARM Cortex-M3 Board Overview and Errata

This is one of the most cheap and widely found ARM board in the market, also known as minimum development board or simply core board. But if you are the proud owner of one like that in the image, I have bad (and good) news for you!

The Bad

These boards are manufactured by LC Technology, they seems to be fine and work well, but there a problem, they have the BOOT1 and BOOT0 pin header, so what? Well, these boards have a STM32F103C8T6 ARM microcontroller, which has just the BOOT0 pin! so the BOOT1 pin header is useless and can confuse you easily, because this board is the choice of many ARM starters and learners.

But this is not so serious, the problem is that the BOOT1 is connected to the BOOT0 pin of the ARM, they are inverted! so pay attention and don't throw your board through the window if you were playing with the BOOT pin and gave up!

The Good

These boards can be supplied by the USB energy from a USB<->Serial cable or direct USB connection too. As we can see in the image, the UART1 pin header is there, accessible and ready to use, just connect the cable and the 5V from USB will pass throught the AMS1117 3.3v voltage regulator, which indeed supply the ARM chip.

The board has JTAG support, that's very useful for use with some external debugger/programmer, like the Ulink2 that is compatible with the Keil uVision IDE. But this is not really necessary, you can program it using the built-in bootloader, through the UART1 connection.


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