Print PDF
Favorite
Email
Step 8Correction!!!
Here's the correction. Oops... update. See next pic.
You should have another npn transistor to buffer the port from the potentially hazardous voltages at the pnp's base. This is depicted in the top left. Collector does not attach to a pullup resistor. The pnp base is already pulled up to Vpp. Emitter is grounded. The collector connects to the 5k base resistor of the pnp transistor. I also show the 10k pull down resistor that I omitted earlier. I still don't know what it's for, though. :)
Because you are buffering with the use of inverters, when you use a TAIT compatible programming softare, you will need to go into the programmer settings and invert the clock, data out, and data in. Because you double invert the Vpp line, you will leave it alone.
FYI, the original TAIT uses DB25 pin 4 to control Vdd. I don't like this, because then you can't run your pic from the programmer's power source. I have added a manual switch in some of my other progammers, but it never gets used. Why would you go behind your computer to turn your circuit on/off? I just add a switch to my breadboard/circuit to control Vdd. You have to disconnect power or the icsp cable when not in use, though, so as to avoid shorting power and ground.
You should have another npn transistor to buffer the port from the potentially hazardous voltages at the pnp's base. This is depicted in the top left. Collector does not attach to a pullup resistor. The pnp base is already pulled up to Vpp. Emitter is grounded. The collector connects to the 5k base resistor of the pnp transistor. I also show the 10k pull down resistor that I omitted earlier. I still don't know what it's for, though. :)
Because you are buffering with the use of inverters, when you use a TAIT compatible programming softare, you will need to go into the programmer settings and invert the clock, data out, and data in. Because you double invert the Vpp line, you will leave it alone.
FYI, the original TAIT uses DB25 pin 4 to control Vdd. I don't like this, because then you can't run your pic from the programmer's power source. I have added a manual switch in some of my other progammers, but it never gets used. Why would you go behind your computer to turn your circuit on/off? I just add a switch to my breadboard/circuit to control Vdd. You have to disconnect power or the icsp cable when not in use, though, so as to avoid shorting power and ground.
| « Previous Step | Download PDFView All Steps | Next Step » |
 |
Add Comment
|
