Junebug Assembly Tips

[Krumlink]

Do you know the part # for the USB Port from MOUSER?

I am going to order from Mouser this time. I really like their website.

 

[blueroomelectronics]

Digikey part number for the USB-B RA connector is WM17131-ND
Or the giggle giggle Assmann version AE9925-ND
**broken link removed**

 

[blueroomelectronics]

Watch out for Mousers shipping and handling charges.
Mouser 737-USB-B-S-RA

 

[Krumlink]

Watch out for Mousers shipping and handling charges.

What is that about?

 

[blueroomelectronics]

I ordered from mouser once, had to pay $35 in duties and broker fees. Digikey no problem. Might not apply to US orders.

 

[3v0]

I ordered from mouser once, had to pay $35 in duties and broker fees. Digikey no problem. Might not apply to US orders.

It does not apply to the US.

If Krumlink can chill out for a bit I wil provide a full list of part numbers (as best I can). Should have time to work on that this weekend.

 

[3v0]

Krumlink was in the process or replacing the SIPs with single resistors and had used a 330R instead of a 100R. I do not recall which resistor that was. I suggested he pull it and replace it with a 100R which he should buy.

On the schematic, 3v0 said that the R3A-E Resistors was mixed up with R2A-E.

When Krumlink and I spoke I was looking at R2A that comes from AN1 on the processor and is used to monitor target power on CON2 3&4. The schematic I am looking at shows R2A as 4.7K.

The BOM for the SIPs shows
R1 10K x 5 SIP 10pin 5 independent resistors
R2 100 x 5 SIP 10pin 5 independent resistors
R3 4.7K x 5 SIP 10pin 5 independent resistors

Howver I would like to have looked at it much more closely prior to saying anything in public. Made sure I was looking at the latest version of the schematic etc.. Sorry.

 

[Nigel Goodwin]

Typical design shown below.
**broken link removed**

Hello, a picture from one of my websites!

 

[blueroomelectronics]

Thanks all of you for the part number fixes, I guess I need a holiday

And feel free to say in public, it'll get fixed and it's better to fix it while I'm working on the manual.

 

[futz]

I built the processor section (1) of the JuneBug programmer and have it working.

You need to program the PIC18F2550 processor with another programmer such as the inchworm. The procedure can be done on a protoboard with the inchworm connected to the 18F2550. You do not need a crystal but it is a good idea to use a .1uF bypass cap between pwr and gnd.

Good luck.

I assembled mine tonight and, thanks to your post, didn't need to spend hours figuring out what to do to make it work. Works perfectly as a programmer, first try.

Now I have to finish up the tutor section. Still have a few missing parts there.

I ordered trimpots, but the ones I got are too small. I may just bend the leads to fit... And the reset switches are discontinued. I'll probably steal some off some old boards in the junk box.

EDIT: The 18F1320 is blinking LEDs now. Now to get those switches doing something...

 

[blueroomelectronics]

Those small reset switches are common here. Electrosonic, Mouser & Digikey have them. Creatron Inc brings them in cheap from China $0.22

The button under the 18F2550 is for a bootloader and the one on the tutor is manual reset for the 18F1320, you could use it as an input button but you'd have to reprogram it using the ICD connector as the tutor has constant power.

Don't forget to enable the weak pullup on port B for the switches... The IR test program will test button 1 too

 

[3v0]

Bill: I would like to get JuneBug to function as a programmer today. Am I right in thinking that I should use the resistor SIPs as indicated by the parts list and ignore the schematic ?

I have built the programmer part of the Junbug from the schematics. The software reports a short on the VPP line when testing. I will try replacing the sip resistors (I used discrete) with the values from the parts list where they do not agree. The again, it could be a real short and I have yet to find it.

For others building the board. The PK2 software on the PC. From the main menu do TOOLS>Troubleshoot.. This will allow you to test the analog circuits between the PIC and the target. Even generates a 30KHz signal on the clock and data lines so you can look at it with a scope. It is good stuff and I wish they had included it for the ICD2.

futz: Glad to be of help.

 

[geko]

Here's some photo's of my working Junebug as PK2.

**broken link removed**

Note: I've used BC548/557 transistors so they're fitted the opposite way to the overlay. Also used a 470uH inductor and discrete 1/8 watt resistors in place of the SIP resistors.

 

[geko]

One other thing I've noticed on the Junebug.

On the schematics for the Microchip PICkit2 the Target Power LED connects to +5V; on the Junebug it connects to Gnd.

This makes the Target Power LED on the Junebug work with reverse logic i.e. Off when Target is powered, On when it's not.

Fit the LED the opposite way and connect the 330R resistor to the top of R15 (+5V). Here's a photo of my quick fix. (if you've already assembled it I would cut the leads off R8 rather than trying to remove it and be very careful not to lift the PCB tracks reversing the LED)

 

[Mike - K8LH]

Looks very nice. I'm envious.

Have fun guys. Mike

 

[futz]

Thought I'd join in the Junebug photo posting trend
**broken link removed**
**broken link removed**

These plastic "feet" really make it nice to use. They keep it from wandering around the desk and potentially frying itself on some other piece of equipment.
**broken link removed**

And just one of my Inchworm+/Unicorn:
**broken link removed**

 

[blueroomelectronics]

It looks great, nice work, you can now use the Unicorn as an LCD platform if you want.

 

[blueroomelectronics]

One other thing I've noticed on the Junebug.

On the schematics for the Microchip PICkit2 the Target Power LED connects to +5V; on the Junebug it connects to Gnd.

This makes the Target Power LED on the Junebug work with reverse logic i.e. Off when Target is powered, On when it's not.

Fit the LED the opposite way and connect the 330R resistor to the top of R15 (+5V). Here's a photo of my quick fix. (if you've already assembled it I would cut the leads off R8 rather than trying to remove it and be very careful not to lift the PCB tracks reversing the LED)

The Target LED works but is reverse of a PICkit 2. I used the prototype design when testing the layout and switched the anode at the last minute. It doesn't affect operation so I left it.

 

[blueroomelectronics]

Bill: I would like to get JuneBug to function as a programmer today. Am I right in thinking that I should use the resistor SIPs as indicated by the parts list and ignore the schematic ?

I have built the programmer part of the Junbug from the schematics. The software reports a short on the VPP line when testing. I will try replacing the sip resistors (I used discrete) with the values from the parts list where they do not agree. The again, it could be a real short and I have yet to find it.

For others building the board. The PK2 software on the PC. From the main menu do TOOLS>Troubleshoot.. This will allow you to test the analog circuits between the PIC and the target. Even generates a 30KHz signal on the clock and data lines so you can look at it with a scope. It is good stuff and I wish they had included it for the ICD2.

futz: Glad to be of help.

Both the SIPs and resistors will function the same, justs looks a little funky. The resistor values are marked on the PCB for the SIPs. The short could be the VPP cap is too low a voltage (16V, 22uf) make sure the DIP switch is off for testing. You can measure VPP on the ICD connector, there is a large gnd hole that will fit most meter probes in the upper left of the PCB. My VPP measures in at 12.1V

The PICkit 2 is rather well designed, even the standalone software is pretty handy. The UART terminal is pretty cool and supported in the Junebug design.

Don't forget you can name your Junebug (you need to use the PICkit 2 software for this)

 

[3v0]

As I mentioned earlier I am building my JuneBug in three steps. It was tested at the end of each step prior to going on to the next.

1. Get the 18F2550 talking to the PK2 interface. (done - OK)
2. Add the analog parts to allow it to program debug. (done- OK)
3. Add the tutor parts. (to do)

I used 1/8 watt resistors in place or the 3 SIPs.

Tested the JuneBug with a 16F88 target and was impressed with how well it works with the MPLAB debugger. Stepping is quite fast, as is updating the SFRs. Anyone using a RS232 ICD2 (Inchworm) will appreciate the improvement in speed.

The rest of the build is mostly just the tutor processor socket, LEDs, and switches.


Problems:
None that were real. All the parts had the correct pinouts and construction was straight forward. I made a few minor blunders along the way like testing VPP with my DVM on AC. But the O-Scope showed it to be correct, only noticed that the DVM was on AC after I started writting this..

Earlier I posted about a problem with a VPP short. I should clarify that that was not with a real JuneBug PCB. Prior to getting the JuneBug PCB from Bill I had started construction on a JuneBug Clone without the tutor.