ATMega ports / features - clarification

[Dan Purgert]

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I'm about on the brink of expanding past the point of "self-contained
widgets", and into using SPI / I2C / general serial over U(S)ART.

Just to make sure I'm understanding things properly, if we take a look
at the ATMega32u4 datasheet, it says it has

- USB
- 1x USART
- 1x SPI

So, if I was going to use this for something, would it mean that I could
use all three of those features independently? For example,
Communicating to the 32u4 over USB, while having it communicate to some
other chips doing other things via RS485?

Or is it that I can use USB OR USART OR SPI in a project?

Thanks!

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[Josef Moellers]

>
> I'm about on the brink of expanding past the point of "self-contained
> widgets", and into using SPI / I2C / general serial over U(S)ART.
>
> Just to make sure I'm understanding things properly, if we take a look
> at the ATMega32u4 datasheet, it says it has
>
> - USB
> - 1x USART
> - 1x SPI
>
> So, if I was going to use this for something, would it mean that I could
> use all three of those features independently? For example,
> Communicating to the 32u4 over USB, while having it communicate to some
> other chips doing other things via RS485?

That is correct (but the data sheet has the last word)!

USB: D- and D+ are separate pins.
USART: RXD1 and TXD1 are special functions of port D bits 2 and 3
SPI: MISO, MOSI and SCK are special functions of port B bits 1, 2, and 3

So: yes, you can use all three independently and "at the same time".

(but: no, you couldn't use port D bits 2 and/or 3 together with the UART
and/or port B bits 1, 2, and/or 3 together with SPI).

Josef

[Dan Purgert]

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Josef Moellers wrote:
>>
>> I'm about on the brink of expanding past the point of "self-contained
>> widgets", and into using SPI / I2C / general serial over U(S)ART.
>>
>> Just to make sure I'm understanding things properly, if we take a look
>> at the ATMega32u4 datasheet, it says it has
>>
>> - USB
>> - 1x USART
>> - 1x SPI
>>
>> So, if I was going to use this for something, would it mean that I
>> could use all three of those features independently? For example,
>> Communicating to the 32u4 over USB, while having it communicate to
>> some other chips doing other things via RS485?
>
> That is correct (but the data sheet has the last word)!

Yeah, my main confusion stems out of generally sticking to ATTiny x5
chips, which only have that "USI" port (so SPI OR TWI OR ...), as
opposed to the more feature-rich chips.

So, figured it better to ask, before making misinformed errors.

Thanks again!

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