The circuit uses a MAX243 chip but I couldn't find it anywhere. There's only MAX232 available. Do you think it can be replace with 232 in this circuit?
The circuit uses a MAX243 chip but I couldn't find it anywhere. There's only MAX232 available. Do you think it can be replace with 232 in this circuit?
Yes any chip that does RS232 level shifting will work. Just be sure to read the datasheet for the RS232 part you use to find out what size caps it uses if any.
Where do you live ? Need to know that to aid in finding parts. Have you checked the Octopart search engine.
i've build the simple L.A. in just a few days and it is working well. the little disappointment for me is that it doesn't have a software side buffer to save more data.
I figured even if the PIC doesn't have enough resource to store data in it, it could be done at PC side software to store down the data for later analysis. But there's no source code provided for PC side application, so nothing much can be done.
i've build the simple L.A. in just a few days and it is working well. the little disappointment for me is that it doesn't have a software side buffer to save more data.
I figured even if the PIC doesn't have enough resource to store data in it, it could be done at PC side software to store down the data for later analysis. But there's no source code provided for PC side application, so nothing much can be done.
8 channels all that's need is a printer port and an OS that allows direct parallel port access. I think a Win98 machine would work best but I've gotten it to work with XP (with some timing glitches)
As far as i know, it will be always better to do the aquisition on a micro-controller or dsp before sending the data to the PC, (or send it in packets like in USB) because multi -tasking operating systems like window have, always had, and will allways (lol ) have difficulties to be precise with timing down to the micro seconds.
That is only true if the multi tasking is preemptive or time sliced. In the case of win98 once a driver gets control it must give it up voluntarily. That is one of the reasons it was so easy to crash the 98 with driver code.
There were definitly glitches in XP, if it were on 98 with no other software running and a minimal driver set it should be as fast as the processor can run it to a pretty fine accuracy.
I am building a logic analyser with the following criteria in mind:
1- Simple to build for average level hobyist
2- Uses few and cheap components (actually only 2 components: an AVR and a 232)
3- Able to do give the best results, given the two constraints above!
So, as Sceadwian says, yeah, it may not be in the scope of my project, but thanks anyway
Ika, using Windows98 with a faster modern computer you will be able to blow the doors off a micro controller with logic analysis. Feed a good clock into it as well and you don't have to worry about timing issues, just quantization error, which you have to take into account for on a micro controller anyways. No components, free software just wire directly to a parallel port.
Actually it is 0.5mm, I have soldered that and worse by hand on our production boards. I've even lifted adjacent pins and soldered mod wires to them.
**broken link removed**
Makes it real easy, or if you are more sure of your soldering technique:
**broken link removed**
That FIFO would make an 18 channel 150MHz analyzer simple. it runs continuously until 2^16 samples after the trigger event and any old USB peripheral micro can read the results out and send them to the PC.
I think the hardware and micro-controller part is finished once and for all (just for this first version )
The software is almost done, a beta version is coming out soon. I still have to write a little help (maybe it'll be online on my website though..), and allow users to export bitmap screen shots, and save/open data for later analysis.
I've been testing it all the week-end and it was a lot of fun playing with my brand new logic analyzer! i've posted some screen-shots of one testing session..
I'm not sure if the first beta version will incorporate decoding UART/SPI/I2C data buses..
EDIT: can anyone please download the SCNALOGIC software, and tell me if it is working on his OS, as it is made under VB and i didn't include the dependencies and VB runtimes, as they are too big...