Unicorn (Inchworm+ ICD2 USB Upgrade) first look PCB

[blueroomelectronics]

As always, comments welcome on the layout before its off to the PCB shop.
Most part numbers are missing at this point.
**broken link removed**

 

[toodles]

Is it possible or feasible to expand the three pin serial connection to include the rest of the serial pins like SS, SCK, and +5v? It'd be nice to use the one connection for testing i2c, SD card, and other serial projects.

Silkscreening on the four buttons and pot to know where the connect to would be nice.

 

[Mike - K8LH]

Very cool...

 

[blueroomelectronics]

RB0 & RB1 & RC7 are the I2C / 3wire lines, not sure where to squeeze another connector... I could put a GND testpoint near the keypad connector (RB0&RB1 are there but no external pullups)

I'll silkscreen the buttons. RB0, RB1, RB2, RB5

I've yet to see if I can squeeze the PTC fuse on it.

I've also got to double check the RS232/485 pinout

The 3Wire and RS232/485 cannot co-exist but the I2C could. I could remove the Rx termination resistors to make space for a 4 pin connector on the top...
thanks toodles.
**broken link removed**

 

[Mike - K8LH]

Any info' on price and a state-side source for that nice 128x64 GLCD you've stumbled upon Bill?

 

[blueroomelectronics]

They sell it here in Toronto at Creatron Inc for $44, I've seen it at Futurelc for $22

 

[toodles]

Can you use the 5mm+2.5mm placing for the crystal capacitors; the same placing you use for the other ceramic caps? It looks like if they were rotated 90 deg, anticlockwise on top and clockwise for bottom, there'd be enough room without disturbing other parts.

All of the 4550 schematics Ive seen have a 1M Ohm resistor between the two lines going to the crystal, which has only two pins. I'm assuming the three pin crystal doesnt need that resistor. Is it possible to leave optional points for that resistor in case a two pin crystal is used instead, or can it use a two pin crystal as is?

Is there any reason to use a USB A connector instead of a B connector? A connecters always felt flimsy compared to B's; silly opinion, I know. I figure you're prolly doing A's because of limited space between boards. Is using solder jumpers and two more pads a possibilty so it can use either A or B connectors?

I'll be getting a pair of new boards as soon as budget permits.

 

[gregmcc]

looks great - wish I could make PCB's like that

 

[gramo]

Does it come assembled, and with the GLCD/LCD?
Do you need a separate programmer, or does it ship with one (and is that assembled?)


Just noticed that it only has support for PORTA headers, and appears to be more of a serial interfacing tool than a development board, any chance you will enlarge the board and make it more user friendly like the EasyPIC4?

**broken link removed**

 

[blueroomelectronics]

Can you use the 5mm+2.5mm placing for the crystal capacitors; the same placing you use for the other ceramic caps? It looks like if they were rotated 90 deg, anticlockwise on top and clockwise for bottom, there'd be enough room without disturbing other parts.

All of the 4550 schematics Ive seen have a 1M Ohm resistor between the two lines going to the crystal, which has only two pins. I'm assuming the three pin crystal doesnt need that resistor. Is it possible to leave optional points for that resistor in case a two pin crystal is used instead, or can it use a two pin crystal as is?

Is there any reason to use a USB A connector instead of a B connector? A connecters always felt flimsy compared to B's; silly opinion, I know. I figure you're prolly doing A's because of limited space between boards. Is using solder jumpers and two more pads a possibilty so it can use either A or B connectors?

I'll be getting a pair of new boards as soon as budget permits.

The double wide .1" .2" I save for the 0.1uf caps only, those wee 22pf thru 33pf ceramics are usually very small and .1" spacing. I didn't use the double width for those on other boards, just the 0.1uf caps.

The USB A connector (and the Molex KK on the right are right angle) have to be low profile as the unit plugs into the bottom of the Inchworm+ (about 12mm total height) when used as the USB Inchworm+ upgrade. A USB B connector is too tall.

I originally had a USB B connector (I like them too) on the design but it required too much headroom.

I'm still going to try an squeeze a 250ma PTC fuse in there.

 

[blueroomelectronics]

Does it come assembled, and with the GLCD/LCD?
Do you need a separate programmer, or does it ship with one (and is that assembled?)


Just noticed that it only has support for PORTA headers, and appears to be more of a serial interfacing tool than a development board, any chance you will enlarge the board and make it more user friendly like the EasyPIC4?

It's primary design goal was to make the Inchworm+ a full speed USB programmer / debugger. The GLCD / LCD and the experimenter had to not interfere with the Inchworm+ upgrade so I/O was not as flexable as a circuit designed from scratch. Considering its size of 4.2" x 2.6" (identical to the Inchworm / Firefly PCB) it's still got lots of to experiment with.

USB, RS232 or 485, LCD or GLCD with backlight control (backlight can draw lots of current; best used when powered from an Inchworm), built in pushbuttons or external 4x4 keypad (I see lots of alarm terminal designs) the 4 A/D ports (simple & slow GLCD scope but fun non the less) an iButton connector (yes I have a thing for iButtons like you Gramo has a thing for BASIC). An LED (why USB ICD2 clones have this who can say, but an LED is an LED never know when you'll need it for)

The RS485 termination resistors (Rx) may get chopped to add a I2C connector. Their fate has not yet been determined...

The GLCD hangs over the top of the unit and should be removed when transporting. On the other hand it's much more portable than the EasyPIC4 and much cheaper and should have a MSRP of $45 as an unassembled kit. Soldering is fun, and premade PCBs make it easy. The LCDs will be an option just like the EasyPIC4, the GLCD has to be a bottom connector type.

Wait till the tiny Mongoose PCB comes out, parts on both sides!

 

[gramo]

yes I have a thing for iButtons like you

Dude, where do you get your iButtons from, I can't find a 'cheap enough' source as yet

The board sounds great, and usable for both Assembler and PICBasic/C developers, I'd much rather trial this board out

It's a fair price, just a little confused, is this device is a standalone USB PIC programmer? (Not sure if I understood you comments, or if Unicorn and Inchworm+ are the same product)


On a side note, I'm thinking that I2C would have more of a beginner/intermediate demand than RS485

 

[blueroomelectronics]

That's the only problem with iButtons & 1 wire stuff, everybody wants em, impossible to buy. I'm trying to get the local retailer to carry them. They do have a suppliers list on the ibutton site, you can often buy a few from them.

The Unicorn is an Inchworm+ upgrade (I'll post a diagram soon) or an experimenter (can be swapped and reprogrammed)

 

[evandude]

The USB A connector (and the Molex KK on the right are right angle) have to be low profile as the unit plugs into the bottom of the Inchworm+ (about 12mm total height) when used as the USB Inchworm+ upgrade. A USB B connector is too tall.

But a USB A connector used on the device side is against the USB specifications. Not that most people care... But you'll have to use an "unofficial" cable which may not be desirable... But is there any reason you couldn't use a USB mini B connector instead? They're even smaller than an A connector, and don't violate the standard, and you can use a standard A-to-mini-B cable.

 

[3v0]

Kudos on the Unicorn.

That's the only problem with iButtons & 1 wire stuff, everybody wants em, impossible to buy. I'm trying to get the local retailer to carry them. They do have a suppliers list on the ibutton site, you can often buy a few from them.

You can order direct from **broken link removed**.

Maxim/Dallas Direct

Worldwide, Any Quantity

 

[Fred.Amoson]

But a USB A connector used on the device side is against the USB specifications. Not that most people care... But you'll have to use an "unofficial" cable which may not be desirable... But is there any reason you couldn't use a USB mini B connector instead? They're even smaller than an A connector, and don't violate the standard, and you can use a standard A-to-mini-B cable.

I fully agree with evandude. Not only on the standards, but almost everybody has an A to mini B cable laying around, I would need to get an A to A cable special from somewhere.

 

[William At MyBlueRoom]

Unfortunately the usb b connector is too tall, I could probably use a mini usb connector. The a to a cable would be included in the kit.
I'll attempt to illustrate why not a b type shortly.

 

[Fred.Amoson]

I think everybody completely understands that the B connector is too large. Those guys are pretty big. But a mini B should work.

Looks good though, I look forward to getting one!

 

[evandude]

Unfortunately the usb b connector is too tall, I could probably use a mini usb connector.

I understand that, what I suggested was the mini B connector, which are smaller than either the regular A or B connectors:
**broken link removed**
https://www.electro-tech-online.com/custompdfs/2007/05/32005-601.pdf
(datasheet with dimensions)

 

[blueroomelectronics]

The digikey.ca mini-b USB is surface mount, I'll try to fit it on with the A type. I've also removed the RS232 (DS275) and added a socket for a 24Lxxxx I2C eeprom + two 10K pullups on RB0&1. SDA & SCK have been added to the USER connector.