I need to add one more serial bus and I can't change my PCB. Only free pins are I2C pins at 43 and 44, or Arduino 20 and 21. Does SoftwareSerial or any serial bus work with them?
SoftwareSerial lists the following for Mega2560 10, 11, 12, 13, 14, 15, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64), A11 (65), A12 (66), A13 (67), A14 (68), A15 (69).but the schematic says there is (SCL/INT0) PD0, somekind of interrupt?
It looks dark...
Yeah. Not good.
Every PCB can be changed by cuts and new connections.
The Arduino Software serial refenence seems clear, RX is only supported on 'change interrupts'
These are labelled as PCINT0 etc.
I need to check Arduino pins 20 or 21 on Mega2560. Or Package pins 44 or 43. I need one serial port somehow and either this or a new pcb.
srnet:
The Arduino Software serial refenence seems clear, RX is only supported on 'change interrupts'These are labelled as PCINT0 etc.
When I read about INT0, I noticed that it can be configured to work in many ways, isn't Pin change one of them. I atleast thought so.
Pin change interrupts and external interrupts are two different things.
See datasheet on details on that; also on which pins support pin change interrupts (which on the Mega2560 is only a few I remember - it's a bit of an oddball in that respect).
I understand. One question still, is there a way to read a few characters at 9600 bauds from a I2C pin. It can block while it reading, but not other times.
I have peripheral which gives short strings (with LF) sometimes, and I need to check whether it is "open" or whatever we want.
You could free up a few digital by maybe using the analog pins , or you could add, for example, an I2C digital I/O board.
Pcf8575
Is there a way to add 2 jumper wires from pins that support software serial to pins that have external connections on your design?
I have a problem because only unused connector on our board is for I2C 43/44/20/21. The CPU is Mega2560. And our new add on sends serial data. Is there a suitable library, blocking if there is nothing else.
I quess we could add jumpers once or twice, but not for every board. RX2 is free yes, but I wonder who could do it here, I am not not willing to try myself.
Extra boards like I2C adapter, or handmade circuit onto some perforated board would work, but first I would like to check SW only solution. An extra Arduino board is always one possible solution, for a single demo machine.
I asked this in Programming forum also, but is there serial receive library which works on any pin? Without pin change interrupt. 20 and 21 pins have INT0 and INT1 interrupts
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Transmission no problem; receiving is a problem: without interrupts it's very likely you miss the start of a transmission (you have only just over 100µs to catch the start bit, assuming 9600 bps, less at higher speeds).
There is a send only software serial library.
If the was a library that could receive serial on any digital pin you would expect it to be popular.
srnet:
If the was a library that could receive serial on any digital pin you would expect it to be popular.
I don't think the demand for such a library is that great. SoftwareSerial works on any pin of the Uno/Nano/Pro Mini, and there's very little demand for this on the Mega which has multiple hardware Serial already (plus a whole bunch of pins that do support SoftwareSerial - may take a little planning but with that many pins on the Mega that shouldn't be much of an issue).
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