Slim 1.8v to 5v SAFE level shifter for sio

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jube
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Slim 1.8v to 5v SAFE level shifter for sio

Post by jube »

Hi all !
Seen some posts with people messing with the slims sio port, so decided to post this circuit from my experemental ts setup to save anyone blowing their port !!

Its not powered of the port ( its for testbed experementation !! ) but uses port voltage as ref so requires the sio to be initialised ( see excellent sio driver by jean ), its not meant to be a product but using a comparitor ensures minimum loading on the sio technology ( which at moment is unknown but prob nmos?) the potential divider on the max tx should use 0.1% res

By the way i used a tiwanese 393 but any 393 should do.

The full TS circuit and project is complete, have not decided weather to post, not much point if no interest !! Will let interested parties pm me i think?

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J.F.
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Post by J.F. »

There are a number of IR to RS232 adapters out there (meant to be plugged into the computer's serial port). Something like this could be used with one to allow the use of common IR keyboards.
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jean
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Post by jean »

Good job man!!! As soon as i'll get a PSP SLIM i will immediately try this, maybe to adapt my MIDI cable, chatPad or other projects i'm working on!
Stop praising me or they'll think i'm paying you for this! :)))
@J.F. I doubt using one of those adapter could be a straight forward task... i guess data is encapsulated; i remember i used one of those adapter years ago and i had to install drivers = death :( ...MMhhhh i have to get one and investigate
PS: J.F. this will not stop you to contribute something to chatPad proj, is it?? :)
J.F.
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Post by J.F. »

jean wrote: PS: J.F. this will not stop you to contribute something to chatPad proj, is it?? :)
Of course not! Once I get the programmer put together and reprogram my chatpad (and make a cable to hook it to my PSP), I'll work on some stuff for it. At least a pspirkeyb driver for certain.

I've got some parts I need on order, so it'll be a while. Too bad all this isn't available at WalMart. :D
jube
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Post by jube »

A ir to serial circuit is not at all hard but doubt will find a suitable off the shelf item to modify, most will be powered off the serial 9pin dtype at 5v, you will have to do one yourself :)
Will post a circuit for one but you will have to wait to build till microchip launch their 1.8v micro's, then make sure the programmer you have is compatible. For the circuit to be portable and powered off the port completly will have to stick to 1.8v components throughout ~( then obviously the above circuit is not needed )
Been looking at pikey more closly, the v4 pr-relese does not seem fw3.71+ compatible, the installer for the 3.5 version is a kernal mode app for a start so will never run? And a quick glance shows it writes lods of stuff to flash0, scarry!!
But its xmb hooking function cant be ignored, am still learning and switching to a linux distro cos now pissed with cygwin and continual command line typing, cant get any of the IDE's ( eclipe,devc,codeblocks, well actually am trying em all, free and propriety ) to work with psp-gcc within cygwin correctly without continually addapting makefiles paths etc etc, so going to use platform you guys write on, and a naitive ide there.
J.F.
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Post by J.F. »

Making pikey work in 3.71 was considered, but then D_A came out with 3.80 with the NID resolver. That should make pikey work on 3.80+. The problem with the installer is known and being looked into. There is also a problem getting pikey to work in games in 3.80+ that is being looked into. It's not known whether it's just a NID that the resolver doesn't support, or related to the "bug" I've seen reported that you need to add a plugin to pops.txt to get the plugin to work in games.
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Torch
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Post by Torch »

Can you explain why you've used each of the resistors. I need to communicate with PIC 16F877A, but I've only used MAX232 once to convert 5V to 12V RS232.
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jean
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Post by jean »

I cannot remember how man times i repeated this (specifically on THAT italian site's board)... No one needs to use a max level shifter to enstabilish communication between the PSP and a microcontroller. New Microchip's microampere technology allow us to power chip directly from SIO (the fact that my ChatPad hack does work is a proof despite the charge-pump section of its circuit). A voltage adapter like max232 or low power version max3232 is only needed to communicate with true RS232. The PSP SIO port shares with it only the simple asynchronous communication protocol, but it does not share the voltage specification that in RS232 could reach -20/+20 volts. Hope that someone will believe me this nth time i say this.
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Torch
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Post by Torch »

I know the PSP doesn't use RS232 voltages!

I wanted to know why he uses a 232 in his circuit. I couldn't understand the circuit diagram so I was wondering if he somehow adapted it for 0-1.8v to 0-5v for the PIC chips, like it says in the thread title.

I don't need to power the PIC either, its already USB powered. I only have the 2 wires from the UART of the PIC. And this model has hardware UART, its not software simulated with standard IO pins. Hence it probably requires TTL levels to work.
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