Thanks for the link. I have updated the source code on my pag (below) this is my current version (old still). My interface is set up the same way as Sami did his PICLink (http://sami.ticalc.org/). It uses 2 diodes and 2 pullup resistors. This following is a desription of the link protocol used by all TI calcs, it was from a text file called system.txt: II.6 ) The link microcontroler Note: This section was written by Sami Khawam All TI calculators have two open-drain lines. There is a method under Fargo to access each line individually for input and output (see "lowlevel.txt"), but in most cases where byte-transfers are needed, TI's built-in link routines are simple en effective to use. The protocol used by these routines will be described here: When the lines are not active they are high. You should remember that if an end of an open-drain line is pulled-down (connected to the ground) by a device, all devices that are attached to that line (including the device that pulled the line down) will read a low signal even if they are trying to pull the line up. We will assume that Calculator1 (C1) want to send a byte to Calculator2 (C2). The lines will be refered by L1 and L2. In the text "10" means L1 high and L2 low, and "01" means L1 low and L2 high. -In idle mode, both lines are high. Depending on the bit that C1 wants to send, it will pull-down different lines: * .L2 will be pulled-down if the bit is 1. .C1 reads now 10. * .L1 will be pulled-down if the bit is 0. .C1 reads now 01. C1 will wait until it reads a 00. -C2 was waiting for a signal change on L1 or L2. * .If it reads 10 it knows that the bit sent is 1. .L1 will be pulled-down by C2 .Now C2 reads 00. It will wait for a 01 * .If it reads 01 it knows that the bit sent is 0. .L2 will be pulled-down by C2 .Now C2 reads 00. It will wait for a 10 -C1 was waiting for a 00. Now it pull-up both lines. After this C1 will read either 01 or 10. -C2 will also pull-up the lines, and reads 11. -C1 reads also 11. This will be repeated 8 times in order to transfer a bit. This protocol used by TI on their calculators, is an effective protocol. But in most cases you do not need to go through those details when programming, since everything is made by the built-in ROM routines. To learn more on the byte level protocol, look at \doc\ti-prot.txt ---- End Text ---- That takes a bit of looking at to work out what's going on but eventually you will se that it quite an intelligent system because each bit is sort of verified. I hope this was the info you were after. BTW: doesn't look like I2C to me. ___________________________________________ Wesley Moore RMIT - BEng/BApp.Sc. 2nd Year wmoore@cs.rmit.edu.au http://wmoore.tsx.org/ On Wed, 26 Apr 2000, Andrew Seddon wrote: > Is that zip called ti_protocol or something similar. It`s just that I think > you probably have an outdated version if you got it from ticalc.org. Take a > look at http://gtktilink.ticalc.org. The guy who runs that has compiled a > stack of information on the protocol using a DSP board. Quite a lot extra in > his version of the zip as to the one in the archives of ticalc. > > Out of curiosity what kind of electrical interface are you using? Direct > hookups to the PIC pins or pullups/diodes etc. At the minute I have mine > directly connected. > > > >From: Wesley Moore > >Reply-To: pic microcontroller discussion list > >To: PICLIST@MITVMA.MIT.EDU > >Subject: Re: Interfacing TI calc to PIC > >Date: Wed, 26 Apr 2000 13:40:01 +1000 > > > >I have experimented with this and my TI-89. I haven't got anything > >functinal out if it but I know how it works. There is a page on my site > >realating to this however the source code on that page is a bit old. I > >also > >have a zip file that I got just the other day with all the documents on > >ticalc.org relating to the ti protocol, I can send you this if you want. > >If you want a copy of my newest source code I can send it too you > >(assuming I can find it) as well. My page it at: > >http://minyos.its.rmit.edu.au/~s9906768/pic/proj_ti.html > > > >___________________________________________ > >Wesley Moore > >RMIT - BEng/BApp.Sc. 2nd Year > > > >wmoore@cs.rmit.edu.au > >http://wmoore.tsx.org/ > > > >On Tue, 25 Apr 2000, Andrew Seddon wrote: > > > > > Hi, I would be really gratefull if you could tell me where you obtained > >the > > > code for the PIC so that I could have a look through it. > > > > > > >From what I understand it`s not I2C but uses similar hardware, i,e > >pullups > > > two data lines etc. That is why there is a bit of software you can get > >for > > > the calc that allows you to interface to i2c IC`s, with no external > > > hardware. I do have the interface specs, I hooked up a simple circuit to > > > test the way I thought it should work and to cut a long story short it > > > dosn`t. > > > > > > I can`t really find any good source of information, you would think TI > >would > > > publish it. > > > > > > > > > >From: Alan B Pearce > > > >Reply-To: pic microcontroller discussion list > > > >To: PICLIST@MITVMA.MIT.EDU > > > >Subject: Re: Interfacing TI calc to PIC > > > >Date: Tue, 25 Apr 2000 18:14:17 +0100 > > > > > > > >I recently purchased a TI83 as part of the support requirements for a > > > >course I > > > >am doing. I set about looking for what was available on the web about > >these > > > >and > > > >came up with several sites just by entering "TI83" on yahoo. It is > >claimed > > > >that > > > >the interface on the jack plug is I2C, but disassembling the code from > >a > > > >simple > > > >16C84 device that connects it to a serial line for connecting to a PC > > > >program > > > >suggests it is not true I2C > > > > > > > >If you want further info Andrew, I will look out the info. I assume it > >is > > > >one of > > > >this family of calcs you are talking of. > > > > > > ________________________________________________________________________ > > > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com > > > > > ________________________________________________________________________ > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com >