As the title says,
Are there particular things i should know in interfacing an arduino (mega board) with a serial (RS232 standard) device that uses a 0/2.5v logic states instead of 12v?
I've read the exausting "Arduino Software RS232"
but as far as i know, computer serial runs on 0-12v logic states ,and arduino on 0,+5V so it needs a max3323e to make all this possibile.
My question is: what should i do in my case?
Is 0,+2.5V sufficient to trigger a high or low state directly on an arduino? (AKA: can i plug TX and RX directly into the designated pins for softwareserial?)
thanks.
Wiring should be the exact same of the MAX3323 ?
I'm a little confused over the datasheet of the 3231, what should be rs232 input and what should be rs232 output?
I mean...i'm making voltage higher on the arduino from a 0-2.4v device, is the opposite of what the article with rs232 between arduino and a pc serial cable (0-12v) says.
something has to be different right?
(the article is this http://www.arduino.cc/en/Tutorial/ArduinoSoftwareRS232)
i've a portable device with a serial RS232 port that runs on 0-2.5v standard.I would like to connect it to the arduino and make them talk over serial via softwareserial lib or similar.
Those words mean that the device you have generates +12V / -12V signals as defined in the RS232 standard. If it generates RS232 it is these high voltages.
However, you might mean it generates asynchronous serial data at 2.5V levels and you want to boost these levels to the levels suitable for an arduino. If you mean this then you should not even mention RS232 as it has nothing to do with anything and only causes confusion.
mh.. maybe you can understand better than me this doc, about connecting the device (a sony PSP) to a computer.
As already revealed here and here, the Remote port of the PSP is in fact a serial port, and the remote is being handled through a standard RS232 protocol, albeit using [0,+2.5V] voltage instead of [-12,+12V]. Therefore the question is; is it possible to connect the PSP remote port to a PC serial port? The answer is yes!
I want to do the same but instead of the PC i want to use the Arduino!
I found some videos (and a post in this forum) about a French guy making something similar, but he did not pubblished anything usefull on his project.
Right so the error in talking about RS232 was in the original post.
The simplest way of making the arduino's TX output go down to 2.5V is to use a voltage divider. As you want half the voltage then the two resistors would be the same. You need enough to be able to pull the input down to zero so I would suggest using 1K resistors.
For the RX side (into the arduino) then the minimum high voltage accepted is 0.6 of the supply voltage. So if you are running the Arduino off 5V this means it has to see 3V to recognise as a high input. This is outside what you have. Therefore the answer would seem to be to use two transistors. TX output from your device to a 1K resistor other end to the base of the first transistor. Collector 10K to +5V. Second transistor:- base to collector of first, collector to the RX input of the arduino and also through a 10K resistor to +5V.
Both emitters to ground, Arduino ground to devices ground.