No matter how small you make your embedded projects, you still need a way to program the MCU. Standard programming headers can be annoyingly large for those very small projects. [Danny] wrote in to tell us how we can save room on our PCB designs using special spring loaded connectors, rather than large headers.
There are so many small embedded development systems, such as the Trinket that still rely on standard headers. Reducing the size of the programming headers and interface headers is an issue that deserves more attention than it currently receives. Based on Tag-Connect, a proprietary connector built around pogo-style pins, your PCB does not actually require any on-board mating connector. The PCB footprint simply has test-pads that connect with the pogo-pins and holes that allow for a rock solid connection. While the Tag-Connect header is a bit expensive (it costs about $34), you only need to buy it once.
It would be great to see even smaller Tag-Connect cables. Do you have a similar solution? What about something even smaller and more compact? Write in to tell us about any ultra-compact connector solutions you have been using!
It’s not that breadboarding AVR circuits is difficult. But you have to admit that it takes some time to set everything up. We don’t label the top of our DIP chips so that you know what each pin does just by looking. Which means that wiring up the programmer involves pulling out the datasheet. [Vinnie] found the solution to this problem which is to make one of these interface PCBs for each AVR chip family. The long pins make it easy to drop over the top of your microcontroller, which is where the name comes from.
His first stab at the idea was just a hunk of home etched PCB which broke out the programming pins into the 6-pin ICSP standard. This second rendition uses the 10-pin standard and adds a few extras into the mix. He included decoupling capacitors which need to be used in every circuit anyway. There’s a crystal along with its load capacitors. This clock source is a snap to enable by burning some fuses. If you choose to use the internal oscillator instead this hardware won’t interfere. The LED is used to get you up and running with blinky firmware as quickly as possible. He plans to add jumper in the next revision which can disconnect this components from the I/O pin. Now you just need to add a 10-pin header to that USB keyboard AVR programmer and you’re in business.
[Quinn] over at Blondihacks has been working with AVR microcontrollers a lot recently, and wanted a quick way to program the ATtiny13a (her current AVR of choice) while the chip is still seated in a breadboard.
To speed up code revision and testing, she built a small programming header that she calls the Bread Head. The device is wonderfully simplistic, consisting of little more than snappable header pins and a bit of upside-down protoboard.
She soldered six headers to the top (formerly the bottom) side of the board, while a set of eight oversized headers were soldered to the opposite side of the programmer. Small bits of wire were soldered in to connect all of the appropriate pins together before [Quinn] slipped the header snugly over the top of the ATtiny and gave it a quick test. Everything worked perfectly, so she slathered in in epoxy for sturdiness and called it a day.
She says that the programmer works so well that she’s likely to make a similar header for other common AVRs too.
Don’t get us wrong, printable whistles are cool and all, but these printable header shrouds make us think that filament printers like the Makerbot and RepRap might just be worth their salt. This utilitarian purpose is a departure from the souvenirs, toys, and art that we’re used to seeing from the expensive development
The six and ten pin header shrouds are designed for a snug fit that makes it easy to glue them onto the plastic spacers of male pin headers. We use IDC plugs and ribbon cable all the time in our projects, but never seem to order shrouded connectors; this is perfect for us. It makes us wonder what other PCB-friendly printable designs we’ve been missing out on? Surely someone’s been printing stand-offs with threaded inserts, right? If you know of something useful that we can share with the rest of the readers, don’t hesitate to send in a tip.
[via Dangerous Prototypes]
[Zibri] found a very simple method for using brain waves as a controller via a DB9 serial port. He’s using Uncle Milton’s Force Trainer which we saw yesterday in the brain controlled Arduino. In that project the Arduino tapped into the LEDs and interfaced those signals with a computer via USB. This time the connection was made using an RS-232 transceiver to pass data from the programming header inside of the toy’s base unit to a computer over the serial port. Tapping into the programming header has a lot more potential and should be more reliable than sniffing logic out of LED connections. [Zibri] has written an application to display the received data but it doesn’t look like he’s made the code available for download.
Apparently he tipped us off about a week ago. We recall seeing this submission but as you can tell it’s a little bit light on the detail. So if you want your tips to be at the front of the line, make sure you do what you can to fill us in on all the details of your project. At our request [Zibri] provided a picture of the PCB from the Force Trainer’s base unit. See it after the break. Continue reading “Mind control via serial port”
[Alex] was frustrated by the amount of time it took to start prototyping with an AVR ATtiny. To make things easier, he built headers that carry the 8 and 20 pin chips and plug directly into breadboards. The boards include a 6pin ISP header, resonator, pull-up resistor, reset, and blocking caps. The ATtiny2313 version also has a serial connection header. This is a prototype though, and he forgot to route one of the connections. He plans on having a large batch of boards ready for next month.