The JeeSMD is getting a new name:
JeeSMD is OUT, SMD Kit is IN!
The new product link is https://jeelabs.org/sk1 (was “js2”). The SKU label and link on the PCB will be updated later, in the next batch of boards.
The new shop link is https://jeelabs.com/products/smd-kit (was “jeesmd”).
All in the name of progress…
This is long overdue…
If you have one or more JeeSMD v1 boards, which look tike this:
… then you are entitled to a free upgrade to the new JeeSMD v2 board, with the fixed VR (and tented vias):
Actually, I won’t send you a replacement board for each one you have, but an entire JeeSMD kit.
Likewise, if you ordered one or more Carrier Boards with Boxes, and never got these:
… then I owe you that DC Power Jack and matching connector. Ignore the 0.1 µF ceramic capacitor if you already have one – it’s for adding the reset circuitry on the Carrier Board’s FTDI connector.
Email me (please include the order number if possible) and I’ll get it out to you. No questions asked.
Mistakes happen – and I can’t undo the past. But I won’t walk away from my responsibilities either.
Yesterday’s post was about assembling all the SMD components of the JeeSMD kit.
The last step is to program a sketch into the ATmega. This isn’t as straightforwards as with a JeeNode, because there’s no on-board FTDI or USB serial port hookup.
It’s fairly easy to create an FTDI connection, but even if you do, you’ll still need an ISP programmer to install a boot loader (see this recent post for some background).
So let’s hook up an ISP programmer first:
I’m using a somewhat weird setup: first of all, my cable connector was attached the wrong way around, so I always have to use this one in that weird folded-over position.
But a more important issue is that the ISP connection needs to use pins 1..6 of the 2×4-pin SPI/ISP connector on the JeeSMD. That doesn’t work with normal flat cable connectors, which assume 2×3 pins and are too wide to fit in a 2×4-pin header. My solution is to insert wire-wrap pins the wrong way around into the cable header. This effectively extends the connector, but now it won’t be as wide and it’ll fit just fine. Another solution would be to only solder 2×3 pins in the SPI/ISP position – you can always add two more pins later.
Once you’ve passed that hurdle, you can use any ISP programmer you like. There have been several posts about this on the weblog, as listed here.
Now, if you want to use FTDI, then presumably you just uploaded a bootloader into the ATmega, with all the proper fuse settings, etc. The next step then, is to somehow connect to a 6-pin FDTI header.
There are several ways to do this. The one I use nowadays, is through a Carrier Board, which includes the 6-pin FTDI connector:
The point about the FTDI connector, is that it’s almost trivial. All you need is 4 wires to GND, PWR, TX, and RX – plus a way to reset the board from the RTS signal. The clever way to generate a reset is to insert a 0.1 µF capacitor between the serial side RTS and the ATmega’s reset pin. Tiny trick, huge implications (does the name “Arduino” ring a bell?).
So how does the Carrier Board implement FTDI? Easy: it adds the capacitor. And you can easily do that yourself without a Carrier Board. Here’s how:
Note that what FTDI calls “RX” is connected to what the ATmega calls “TXD”, and vice versa. It’s all a matter of perspective… Once you have the FTDI connection set up, you can upload sketches using the Arduino IDE just as with any other board. All you need is a USB-BUB or some other equivalent USB-to-FTDI interface.
Congratulations: that’s all it takes to build and use the Arduino-compatible JeeSMD!
The JeeSMD is a kit with tiny “Surface Mounted Device” (SMD) components. SMD was designed for automated assembly with Pick & Place machines, but with a bit of patience it’s fairly easy to assemble a board by hand – see this post for an overview of what you will need.
You won’t be able to do this without at least a fine-tipped (0.4..0.6mm) soldering iron plus the following tools:
A magnifier lamp also helps, I know I couldn’t do this without one anymore!
This is a step-by-step guide on how to assemble the SMD kit, which consists of these parts:
The tiny ones (don’t sneeze!) are hardest to tell apart:
(thanks to Steve E for the macro shot – I just added some labels)
There are 2 10 kΩ resistors in there, although you only need one. That lets you get started without having to worry too much – if you mess up completely, just remove it and start over with the other one.
For a fantastic resource with detailed videos about hand-soldering SMD, see this Curious Inventor page.
So let’s get started. First thing to do is to apply flux wherever you’re going to solder things. The flux is essential because the flux in your solder wire will have evaporated longe before you can move your tip from the wire to the part.
I’m right-handed, so that’s how I hold my soldering iron. That leaves only my left hand for the tweezers – and no hand at all for the soldering wire:
Use your tweezers for all these parts, and don’t let go – once a 0603 part flies off or drops on the floor, your chances of finding it again are next to zero. Best is to work on a clean flat surface with everything around you removed.
The trick is to place the part and then push it down while you touch it with your iron with solder already on it. The moment a part is soldered down on at least one pin, it becomes a lot easier:
The matte “stain” you see around these pads is the flux, which has dried up but is still active.
(Remainder continued after the break…)
Meet the new kid kit in the Jee family – the JeeSMD !
At a glance:
What’s the point? Well, it’s going to be made available as an SMD kit, and it’s going to be low-cost. If you don’t care about wireless or FTDI, then this is a convenient and compact way to hook up some Jee Labs plugs.
Of course, all the other stuff fits as before, including the Proto Board, for example:
Here’s the board in more detail:
(don’t look too closely at this prototype PCB – there are some silly cosmetic mistakes…)
There are some trade-offs w.r.t. JeeNodes:
I’ve got a few boards for people who want to get their hands on them. The kits will be ready in about a week.
Now the JeeSMD kit needs a detailed set of instructions and close-up shots on how to assemble and start using it – more work to do!