serialin

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

it semms a misnomer not really but it can be confusing
serialin1 corresponds to com2 and not to com1 as indicated in the help

albertsm · Joined: 09 Apr 2004 Posts: 5922 Location: Holland

yes it can be tricky. when i made bascom-8051, most users knew about GWBASIC and it used the PC com port : COM1.
So in order to make it simple, i used the same convention : COM1 for the UART.
For the AVR i used the same method. And the first AVR processors only had 1 UART. And al UART registers did not had any number so the world was simple.
When there came processors with 2 UARTS i used COM2 for the second UART.
Atmel named the second uart with an 1 so there was UDR and UDR1.
Later they renamed to UDR0 and UDR1 using base 0.
So then i used UDR and UDR0 to be equivalent.
But somewhere i goofed up for the SERIALIN/OUT.
The problem is that i can not change it anymore since it would break code. I thought about a switch/option but that will also result in a support nightmare.
So, sorry, this is one of the things i wished i had paid better attention to.

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

I think most of the problem is with Atmel. If they had called the Uarts 1,2... etc then most of the problems would have been fixed. But of course they probably think in ASM, like me, where the base address of anything is always 0, and higher addresses in the array are base + 1, base + 2 etc.

I struck this years ago on a unit where we only used 1 Uart originally, so called it Com1. Then we expanded to 2 Uarts, and I decided to assign Com1 = Uart1, Com2 = Uart0. That caused endless confusion later on.