EPPO Hardware

Building the EPPO hardware. Tips and Tricks. Troubleshooting and measurements.

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How do I build the EPPO?  eppo_400.gif
EPPO comes as a DIY-kit in some sort of packaging. Amongst all nescessary components, you will find a comprehensive manual on how to build it. The photo on the right is the second prototype in existence, next to the veroboard one which is promoted to the bin. Since this one is a prototype too, we didn't know if there were parts which needed changing, or if we had to cut or otherwise modify tracks on the PCB. Some parts I used, came out of the recycling, such as the elco's. You can clearly see that the zenerdiode of 5.2V was not in my posession, so I combined a 4.7V zener and a 1N4148 diode, to get the same result. The leads of the 100n capacitors had to be bent to get them fitted right. The 28pin DIL socket is reprodiced using two 14 pin sockets, and the actual EPPO controller (IC3) is on a socket as well. This prototype has a PIC12F675 fitted instead of the regular PIC12C672. The two transistors I used, also came out of the junkbox, and are of the type BC327 instead of the ones that come with the kit. As you can see, there is a target controller inserted in the 18 pin socket. At the making of the photo I forgot to remove it, my apologees for that one. The only thing you need next to the kit to get EPPO working is a 15 to 20 VDC mains adapter. Maybe future versions of the kit have an adapter included. I presume that you know that EPPO won't work without some kind of PC with at least one free regular COM-port. Connect EPPO to the PC using the 1:1 RS232 cable supplied with the kit.

Without installing EppoManager, how can I test the hardware?
Eppo_connectors.gif If you connect EPPO to the free COM-port of your computer, please run some kind of terminal program. Set it to the richt COM port, at 19200 Bd, 8 databits, 1 stopbit and no parity. (remember to reconnect if you use Hyperterminal) If you power up EPPO, with connection power to it, you should see the green powerled come on, and the VPP led flashes three times. At the same time, you should see EPPO announce itself on your terminalprogram, by sending "Eppo". If one or more indications fail, you have a problem. The photo on the left is a little strange, isn't it? I'll tell you why later. In this photo you see the firmware socket IC3 at the top- right, and the home-made zener Z1 at the top- middle.To the left of the dB9 connector is the power supply circuitry. The circuit around the HIN202 handles the conversion from TTL to RS232 and vice versa. The two transistors at the top-middle drive the VPP and +5V signals, and the VPP led. All three elco's are part of the powersupply. As you see, most of the important texts are printed on the board, so even without a manual you could get EPPO working.

The powerled doesn't work. Now what?
First of all, if you reverse polarity of the mainsadapter, you can not blow up EPPO, D1 will see to that. So first check if the polarity of your adapter is ok by using a multimeter. The inside should be positive, and the outside should be negative. The voltage must be a minumum of 15V. Off-the-shelve 12V adapters normally give 15V, you should be able to use one of them. Check if D1 is the right side around.

The VPP led does not flash. Help!
 The flashing of the VPP led indicates that the software is running. Did you insert the EPPO firmwarecontroller the right way? Please ensure that the notch on the chip faces inwards, from the side of the PCB. Did you insert the correct controller? The DIY-kit comes with an empty controller to play with. Is the led mounted the right way around?

Why don't I see anything on my terminal program?
The software on EPPO is working, so it will send data to the RS232 driver. Ensure that the driver is mounted correctly, and you have used the 1:1 RS232 cable which came with the kit. Now check if your terminal program is working, by removing the RS232 connector at the EPPO side, and shorting pins 2 and 3 with a paperclip, a screwdriver, anything metallic. If you type something on your keyboard, you should see the characters beeing echoed. If not, you should check all terminal parameters before you try anything else. If you see garbage appearing on your terminalscreen when you connect EPPO and powering it up, check your portsettings again.

Where do I put the microntroller to be programmed?
 prog_bay_400.gifprog_bay_2_400.gifAs you know, EPPO can handle 8 pin, 14 pin, 18 pin and 28 pin (narrow) microcontrollers. In both photos you can clearly see the 28 pin socket (made with 2 14pin sockets) which will only fit the 28 pin controllers. You can see how a 8 pin microcontroller has to be fitted. A 14 pin microcontroller must be fitted the same way, and the same again for the 18 pin microcontrollers. Bigger microcontrollers must be programmed via the ICSP connector. The design with the controller must have a simple similar interface, so you can connect EPPO to the circuit with a 5-wire 1:1 cable. Note. Do you see something strange about the photo on the right? (and also with one of the photo's above) If you went to a technical school, and had to draw mechanics by hand with pencil and ruler, you had to do so in so-called "american projection", so completely without perspective. You can see the PIC12F675 microcontroller to be programmed in its socket. The "empty" controller which comes with the DIY-kit is supposed to be run in the Led Bar Demo Board. The Led Bar Demo Board is initially part of the EPPO PCB. The right photo shows a jagged edge on the right side, where the Led Bar Demo Board has been broken off. (that's it's purpose) So the Led Bar Demo Board has a jagged edge too! This can be quite sharp, so if you want to do some filing or sanding, be my guest. The VPP led is a red one. Not that it signals a dangerous situation, but it's a sign that programming, reading, or erasing can be executed at the time. On the right photo you can see a thick white line on the left, which divides the actual programmer (not on the photo) and the programming-bay, where you are allowed to put in and remove microcontrollers as you wish. You can imagine that, if the EPPO firmware is in a socket, you could remove that one, and put it in your own circuit. That might be a reason for you to ommit the socket for IC3.
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