PIC Interface Test Software - Now available

[Eric Brouwer]

I have added a program to test the PIC Serial interfaces on my web for those interested.

Just click on "Homepage" below, and go to Interfaces on my web.

[chioccio]

I tried to make the pic interface, i connected it to the Pc but testing it i have reversed voltage to the pic input I mean where there should be a positive there is a ground and where there should be the ground there is a positive. I tried to test the serial port pinouts and it looks like it carry out only negative voltage (-10 V) Thank in advance to anyone will help me.

[Eric Brouwer]

Hi Chioccio

It's unclear as to what input on the PIC you are refering. If it's the input from the radio, it might be that the connections needs to be swopped on the cord running from the radio to the interface. i found that sometimes it works better connecting the radio signal in reverse, especially on some JR radio's.

On the serial output of the PIC (pin going from the transistor that is connected to the DB9 plug), the voltages should be reversed. With 5V applied to the base of the transistor, you should get anything from -5 to -15V on the RXD line (pin 2). Applying 0V to the base, should give you around +5V on RXD line.

As a PIC works on a TTL level (either 5V or zero volt), and a serial port works on RS232 levels, an interface is required to connect a TTL device with a RS232 device. The transistor is used to act as a converter between TTL and RS232.

My advise is to measure the voltage on the PIC (across the zener diode). If you do not get at least 5V, you might want to change the resistor between pin 7 on the DB9 plug and the zener diode with a 470ohm resistor. Furthermore, try replacing the 4K7 resistor between pin 2 and pin 4 with a 47K resistor.

Also ensure that you use the correct transistors (NPN or PNP). Have a look at my Joystick/PIC design (just click on "homepage" below). I have tested it on quite a lot of different PC's and radio's, and it work correct on JR and other radio's.

Hope this might help.
Hope this might help you

[chioccio]

Got it!!! Now the Voltage at the Vdd Vss pin of the 12C508 is a 5.5 V which should be satisfactory (i had mounted the D1 (5,6 V) upside-down). Now the problem is that the interface is not working
I use Windows XP, i have an Hitec laser6 radio, i connected the wiring to the radio as stated on the readme_en.htm file (looking to the back of the radio i put the pin 2 on the top left, i connected 5 and 4 (the first and the second to the right) together and i connected the ground on the pin 6 (the one in the middle) downloaded from fms site i chose the first schematics (12c508, 9 pin connector db9 female). I changed the Q2 (KT3107) with a KT 3102 since it looked like it was an error in the schematics.
When i start FMS, i have no signal on the blu bars when i try to calibrate. I use Com 1, 8 19200 bps; 8N1; Xon/Xoff.
I also tried to use your pictester program but i get 'No PPM signal'.
Thank you in advance for your help.

[Ken Hewitt]

Two things to check for.

1. The 0v on the 6 pin Din plug is usaully on the metal screen not pin 6 as stated in some places.

2. You did program the PIC correctly with all the right options.

Ken.

[chioccio]

I'm done, i had put the KT3107 (BC557) upside-down poor babe Thank u everybody for your help. P.S. i used the pin 6 for ground, Q1=BC557, Q2=BC747 or BC546.
Bye bye from Max, Italy.