In newer versions of the language, there are ways to explicitly specify the bit width in this case uint8_t would do the job. Using traditional C data types, our example register would be declared unsigned char. It is almost 100% certain that a register will be unsigned and its size (width in bits) must be accommodated. There are a few important matters to get right when accessing device registers from C. Bits 3-4: parity, where 0=none, 1=even, 2=odd and 3 is an illegal setting.Bits 0-2: baud rate, where the values have specific significance.There may also be bits that are unused – reading from them or writing to them normally has no effect.įor example, a serial interface (UART) might have an 8-bit register, with the bits used like this: Such fields may be single bits, groups of bits, or a whole word. Typically a device register will have bit fields – groups of bits that contain or receive specific information. These normally appear just like memory locations and can, for the most part, be treated in the same way. A peripheral device is likely to have a number of internal registers, which may be read from or written to by software. The broad issue is quite straightforward. This article looks at how C may be used to access registers in peripheral devices.
#Saving input from serial uart embedded c program code#
The ability to write code that gets close to the hardware is essential and C provides this facility. One of the key benefits of the C language, which is the reason it is so popular for embedded applications, is that it is a high-level, structured programming language, but has low-level capabilities.
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