We will eventually need to communicate to our processor with asynchronous serial

Question

We will eventually need to communicate to our processor with asynchronous serial communication. Let's say we really need to communicate at 28.8 Baud. Will our selection of system oscillator affect our ability to achieve this goal? To answer this, you will need to know the tolerance of the oscillator, and see what effect this has on the Baud rate. The ATmega328P datasheet contain useful information in Chapter 20, especially in Tables 20-1, 20-2, 20-3, and 20-7. You should only consider receiver error, and will need to do math to have a complete answer. Assuming we are making an alarm clock, we will be tracking real time. Can we effectively do this with the system clock at 8 MHz? 16 MHz? What sort of error may accumulate given your selected parts?

Explanation / Answer

Table 31-6 from the datasheet is reproduced below. Bits 2-0 are used to set the boot size for the ATmega328P; boot size refers to the amount of memory reserved for the installation of a "Boot Loader" similar in function to the bootloader used in the Arduino line of development boards. The purposes of the remaining bits in the Fuse High Byte are made reasonably clear by the table entries. The two bits to be avoided unless you are absolutely certain you know what you are doing are bit7, the RSTDISBL (external reset disable) bit and bit 5, the SPIEN (Serial Peripheral Interface Enable) bit. Disabling either one is often the cause for "bricked" Atmel µCs; "leave them alone" is good advice.

There are a total of 19 fuse bits that are used in the ATmega328P, and they are separated into three different fuse bytes. Three of the fuse bits are contained in the "Extended Fuse Byte", eight are contained in the "Fuse High Byte," and eight more are contained in the "Fuse Low Byte"

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