Small Serial Communication Help

NewEmployee · Post by **NewEmployee** » Thu Apr 03, 2008 7:33 am

Hello there, I am a computing & electronics student. I have recently started a small hardware and software project. I am creating 4x4 button inteface. This inteface is a base for my first drum machine. The psp will be the heart of this drum machine.

You are probably wondering why I have stumbled into your premises. Even though some of what is required to finish this project is taught in my course, I do lack practical experience. Namely serial communication, I have learnt a whole load of theory but have no reference on how I should implement this.

Now, hear, I could go into great detail about my project but I'll keep it short and simple. Could someone please demonstrate how in practical terms how I would send the letter 'A' from a microprocessor to the PSP and any more hardware I would need to build, I have seen a circuit comprising of a MAX3232. I am using a PICAXE28X Microprocessor that is a PIC chip with a custom bootloader and utilizes a basic compiler opposed to the industry standard C. It uses RS232 to communicate, but at 0v and power supply which is 5v.

Again, this maybe very easy to achieve with both the psp and picaxe working on RS232, but any help would be greatly appreciated.

jean · Post by **jean** » Thu Apr 03, 2008 7:57 am

see http://forums.ps2dev.org/viewtopic.php?t=9804

good luck!

jean

NewEmployee · Post by **NewEmployee** » Thu Apr 03, 2008 8:30 am

Many thanks to you good sir! I really should have lurked more before submitting my thread.

Art · Post by **Art** » Thu Apr 03, 2008 7:57 pm

This might be closer to the hardware you want for a drum machine:
http://forums.qj.net/f-psp-development- ... 41254.html
although it's 3X4 matrix,
the shift key could be replaced with a toggle switch to provide 12 more functions.
Art.

NewEmployee · Post by **NewEmployee** » Fri Apr 04, 2008 3:00 am

The Great ART?! Your hardware porjects are an inspiration to us all.

I have already built the circuit albeit connection it to the psp. Here is a screenshot of the pre-build simulation.

Because the PICAXE is just a modified PIC Chip, I should be able to just map your PICout-PSPin right?

Just researching the psp serial port spcifications with the help of my friend he should be able to help me get it sorted shortly.

jean · Post by **jean** » Fri Apr 04, 2008 6:00 am

...mmmmhhhh....i don't know where this scheme comes out, but i see it's using analog sampling to do binary on/off discrimination...If it's your work , Art, forgive me: i appreciate you and all your work, but this can be an electronic homework/curiosity...in the real world this has to be handled by matrix muxing/polling (pic generally have all the i/o pins needed and they don't even need buffers!) like in all keyboard you can find under the sun! ;P

Art · Post by **Art** » Fri Apr 04, 2008 6:55 am

I don't know wtf that is, but it doesn't resemble anything of mine, and def won't run my pic code.
I may not be able to draw a schematic, but I can connect a keypad to a pic ;)

jean · Post by **jean** » Fri Apr 04, 2008 8:40 am

it doesn't resemble anything of mine

I was sure of it!!! my fault, i was in a hurry and i didn't take a look into your link, too....

NewEmployee · Post by **NewEmployee** » Sat Apr 05, 2008 2:21 am

That is the cicruit I designed. I am on my second year of my A-level course and this is what I designed with my course material. That is why I asked for help because I haven't had any real example of serial communication just some theory.

I am just using a load of push to connect buttons onto a summing ciruit to minimise my analog inputs as I want to expand the project after I get the initial idea working.

Ignore my idiocy about just copying your connections into the psp. I just need to know how it is connected and what pins. Should I just be abe to use the send and recieve lines of the picaxe chip into the send and recieve pins of the psp? I have seen some difficulties with this as I saw a thread somewhere where someone could not balance the logic values.

I just wanted to build a cool circuit for myself. Please help me rectify any problems you can see in my ciruit. If it is optimisation (e.g keypad matrix or WTF is a Op-Amp their) please leave it out, I want to b e able to understand my circuit. Can you see anything that is not real world friendly. I know the R value for the mixer ciruit is a 1K in serial with a 24R. I have built most of the ciruit already.

jean · Post by **jean** » Sat Apr 05, 2008 2:49 am

I don't understand your english very well, and -most important- i can't understand what do you want: if we have to leave out our observation about things you did in a strange manner (no one would use analog input in that way if he does have all that pic's i/o pins free...) then HOW can we tell you the out-of-real-world issues about your circuit? You got all the infos you need: refer to Art's circuit here for hardware, and take a look to "psp advanced sio" source i posted in the thread linked above for what concerns software. Hope you can do a good work.

jean

NewEmployee · Post by **NewEmployee** » Sat Apr 05, 2008 2:54 am

Yeah, I'll soon figure it out myself. See you soon.