Recent blog entries for Varney

Well it is a long story but I am currently bed bound due to a back injury. The good news is that this has given my time to work on some designs for my next project. I plan on hacking my robosapien, I think a couple more brains will do him some good. I will post more details later.

I got it working! YAY! Last night after I made that post I discovered that whenever I touched /LE on the latch and hit reset (with the RC circuit) it would work fine. Confused I went to bed, and stared trouble shooting it this morning. After several hours of being totally confused I finally figured it out, I had the ground wire for the latch ran right under the oscillator; this was causing so much noise on this chip that it refused to work. Once I moved the wire everything was fine. It is nice to have this done!

Been a while since I checked in here. my It has been a while since I have been around here, but not a lot has changed for me. Right now I am working on what is nicknamed the ¡§junior project¡¨ for school. Basically we have to wire wrap a simple embedded micro system, and to get it checked off we have to demo it as a clock. The board contains: 80188EB micro, 256 eprom, 256 sram, 373 latch, an 8255, and a LCD.

I have the entire thing wrapped, but I am having major issues with the reset circuit. The 80188EB is EXTREAMLY touchy about its reset input. I have tried several different circuits including a RC circuit ran through a Schmitt trigger, and a TL7705 reset chip. I dontt understand the TL7705, twice I have wired it just as the data sheet show, however I get 2.5 volts on reset and /reset at all times. When I trip the /resetin I get about 1.3 volts on both pins. This makes no since to me since I have seen many people use this chip on their board with no problem. Out of several thousand resets (with the RC circit) I have only got it to work right twice, and both time it ran for more then 30 minuets, so I know that I don¡¦t have any problems with my setup (other then the reset that is ). If anyone has any idea on how I can get this thing to reset right please e-mail me at Anime2Envy@insight.rr.com, the project is due by Tuesday f¼

Anyway back to robotics. I have plans to use this board as a robotics platform. I have all kinds of ideas in my head on how I can make it work. I also believe that this robot can be used as my senior project when the time comes. Just need to get the board working first.

Anyway, ¡¥till next time.

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