I have built a JDM style serial programmer using an external power supply to power the pic. I have read the datasheet for the 16F628A and to enter LVP I have to pull MCLR and PGM to high. RB7 is hooked to pin 4 & 8 of the serial port. PGM is to pin 3 with a 10k resistor. If I wanted to use HVP could I not pull PGM high and use 13+ volts to MCLR?
I have built a JDM style serial programmer using an external power supply to power the pic. I have read the datasheet for the 16F628A and to enter LVP I have to pull MCLR and PGM to high. RB7 is hooked to pin 4 & 8 of the serial port. PGM is to pin 3 with a 10k resistor. If I wanted to use HVP could I not pull PGM high and use 13+ volts to MCLR?
Hi,
HVP mode is always available just connecting +13V to MCLR regradless of LVP pin. I strongly recomend to disable LVP mode (it's useless) by clearing/setting LVP Config bit.
I took this from the datasheet of the 16f628A. So far the JDM programmer I built isnt working. According to this schematic it should have power to Vss and Vdd.
Pin 3 of db9 to RB7
Vpp to MCLR ;which right now it is a 10k resister to Vdd
GND to Vss and Pin 5 on db9
Just to check, which db9 pin does RB6 connect to?
Should the +5 be from any of the db9 pins or can I use the external ps?
Try this, I build it myself and it works fine with Ic-prog. I didn't assemble the sockets, I just use ICSP and I have a jumper to select power (from serial port or programmed circuit)
Yes, that's how it works. BUT if you enable LVP mode in config register, you will LOSE one pin of the PIC! You can't use it as general purpose I/O pin... so LVP mode is USELESS.
I once had an LED on the LVP pin of an 16F88 and i was banging my head why the LED is not liting up.Then i found out that LVP was enabled.I hate LVP.
A waste of pins.
Okay I tried Stolz's LVP cable and ICProg with the 16f628A and it is not writting the pic. The cable I have is a bit long. Around 5 feet. Could that be it? Or could it be my serial port?
Okay I tried Stolz's LVP cable and ICProg with the 16f628A and it is not writting the pic. The cable I have is a bit long. Around 5 feet. Could that be it? Or could it be my serial port?
Okay I have tried two different JDM programming software and it keeps failing. I brought the cable length under 6 inches and used a meter to test all connections.
MCLR is pulled high off of Vdd with a 10k resistor.
Vdd = 5.0+ VDC ;external PS
Vss = 0+ GND from ps and to pin 5 of serial port
PGM = pin 3 with 10k resistor
PGC = pin 7 with 10k
PGD = Pin 4 w/10k & pin 8 wo/resister
I am trying to use LVP. Other then the LVP check box on the ICProg is there anything else I need to do? Sorry I am really new to programmers.
I just read a tutorial with another JDM style programmer using ICProg and it talks about WinXP needing special drivers. I never installed those. Could that have anything to do with it?
The configuration word in the PICs memory has to alredy be set to LVP.Then You need to aply a logical high to bouth MCRL and LVP and giving it power suply to Vdd and Vss. Then the programer can start comunicating whith the PIC
While I am hitting my head on the wall because it isnt working I had to ask this. Could the fact that my serial port runs with -11 volts have anything to do with it? Do I need to use a MAX232?