Help needed

[nikki81]

Am having a go at building this http://www.electronics-lab.com/projects/...index.html but am not sure how to program the firmware on the 18f4550 40 pin pic do i need a bootloader on the pic for it to work ?

thanks

 

[davenn]

hi nikki
welcome to the forums

that link doesnt work, so we dont know what you are referring to

Dave

 

[nikki81]

Sorry about that they must have a server problem here is a working link for the project http://www.electronics-lab.com/projects/pc/012/index.html

 

[CocaCola]

You need a PIC programmer that supports that chip to load it up...

If it's just a one off, it's probably best to just outsource the burning to someone that already has the hardware... I would offer but the overseas shipping isn't cost effective...

 

[nikki81]

I use a willem programmer pcb5.0b it supports the 18f4550 with the icsp header

 

[CocaCola]

Then you connect to the ICSP pins and burn...

 

[nikki81]

I've made a icsp adapter and programmed it but when I plug it in its getting 5v from the usb but its not doing anything I've checked my connections and it looks ok

 

[CocaCola]

I've made a icsp adapter and programmed it but when I plug it in its getting 5v from the usb but its not doing anything I've checked my connections and it looks ok

The completed circuit, the programmer or what?

 

[nikki81]

sorry i should have been clearer ive installed the chip in the completed circuit but its not doing anything not even detecting it as a usb device when i plug it in to the pc

 

[CocaCola]

Well welcome to that not so fun side of electronics... You need to go back and double, triple and quadruple check every step you made building, look at the pc board to make sure it's perfect, look at every solder joint, confirm polarity of any parts, confirm values of any parts, confirm all connections, confirm the chip was programmed... It's not a fun path but we all take it...

And first and foremost, clear the "I did it right" or the "I didn't make a mistake" mindset out of your head, we are all guilty of doing it but with that mindset you will in many cases cause you to be blind to the error... You need to approach it with the "What did I do wrong" mindset and find the error...

 

[nikki81]

well ive double, triple and quadruple checked everything and made sure there is no shorts and the pc is still not seeing it. makes me think the pic is not programmed properly are we 100% i dont need to have a hid bootloader on the pic ?

 

[CocaCola]

A HID bootloader would allow you to program it through USB with the computer and appropriate software written for that bootloader... A bootloader simply allows you an alternative way to 'program' the PIC without a traditional PIC programmer... It has no effect on the final product being detected as a HID USB device, that would be done with the firmware as is described in the article...

Maybe some pictures of your circuit will shed some light? Did you confirm you programmed the chip? To do this make sure to not set the lock bits, program and then read the chip and verify that the firmware was written...

 

[nikki81]

am very new to pics what are lock bits ?

 

[CocaCola]

When you program you have the option to lock the PIC so it can't be read, it will be somewhere in the configuration settings of your programmer... If you lock it there is no way for you to read it and verify that it wrote, most software verifies the write automatically, but we are trying to do it manually... Thus make sure the lock bits are not enabled, program, and then read the chip and verify that it took the program...

 

[nikki81]

this is how i am programing the pic with the willem software

1 plug pic in
2 select the device from the menu
3 erase the pic
4 do a blank check
5 load the hex into the buffer
6 load the hex to the pic
7 verify its programmed properly

does it look like i am doing it right ?

 

[CocaCola]

Yeah that appears correct, so that would likely leave you with a build error on the circuit if it's not working... Clear pictures of your build?

 

[nikki81]

 

[CocaCola]

Can you take a picture of the bottom of the board out in sunlight and possible in two sections so that it's better resolution? The glare from the flash make it hard to actually see things...

Also if you have some acetone (real nail polish remover) laying around, take a q-tip and clean the flux off that bottom of the board, so that it's again easier to see...

Since it's a home etched board, did you check continuity between pads before you assembled to make sure there where no broken traces or poorly conducting traces?

 

[nikki81]

 

[CocaCola]

I have highlighted (by no means a complete go over) a few potential issue places, have you checked the continuity of all the traces? Hold this board over a bright light and look at these traces, it will more clearly show the breaks... Also consider taking an iron and coating all the traces with a thin layer of solder to help restore the traces to solid conductors...