I have been working on an infrared remote for a couple of weeks, and I decided I wanted to write a program for a Microchip that would accomplish the task. I started writing a C program to do the heavy lifting and a thought came to mind. I will have no way of controlling the actual timing of the circuit using C. I might get close, but the code could be way off.
I continued to write some stuff in C, but it wound up being mostly Assembly. Then I just went and finished writing another copy completely in Assembly. I used MPLAB to configure the fuses. Configure…Configuration Bits…
I couldn’t take it any longer. I haven’t played in a long time so I decided to start from scratch and design another digital clock. I’m working on the board right now. I had one more display, RTC, and 32.768KHz xtal left.
I am building my own display driver this time though. The display driver will be an MCP23S17 multiplexer and a PIC16F690 microcontroller. The display driver that I used in the Picaxe clock was about $8. Not counting the amount of time I’ve spent writing the code my display driver should be about $2. Plus, I really don’t want to have to buy a driver and then spend the money on shipping when I have what it takes to make something work. We’ll see how it goes. In theory it seems like it will work.
I’ll explain more in a few weeks. I’m also tackling this project to create a C header file for the DS1305. It might help someone else out who is trying to work with it.
Sept. 22, 2009 - Waiting on parts to come in can be boring so I went on a dig through my parts bin and found this LED still in its original packaging. While the packaging leaves a lot to be desired, I actually found the datasheet on RS’ website. I played with this LED and some 1k resistors on a breadboard, and now I’m going to make a night light that changes colors. The original program that I wrote lasts about 15 minutes, and it cycles through all of the colors [edit – at least I thought it would). It uses a rough PWM method that I wrote to fade in and out.
After a little math work I decided on using 20mA for all of my colors. They are rated for 30 to 50 mA depending on the color, but with this I can use the output pins on my PIC12F675. This saves a lot of transistors for another project. Continue reading →
Well, the clock hasn’t work for a few months. When I plug it in and then unplug it, it shows a few random letters. Then it stops doing anything. Well, I figured that the display driver was broke since I noted it acted quirky in the first article almost two years ago. I was wrong.
It seems that we should always start at the wall and begin troubleshooting from there. Always. This is probably rule number 1. Well, it all boiled down to this: the original wall-wart shorted out and burned up. This leads us to the title.
Check out the new power plug. The original wall wart was a 6 volt output. I am now using a 9 volt output since the 7805 IC would prefer a little more voltage. I also did a current consumption test, and this circuit uses less tham 30mA. Now it can be unplugged and transported much easier.
Well, due to eBay difficulties, I was severely delayed in finishing this project. It seems that the person that I ordered my first blue LCD display from didn’t want to send a few folks their stuff this month. I went to check on the status of my order, and there were negative feedbacks from around the time that I placed it. So much for that. They sure were inexpensive. Continue reading →
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