bijouboard

This project has beed pwned by Jockiboard. ;)

The bijouboard will be an ultra cheap and small development platform.

Estimated contribution towards costs for members: 3,50€ á kit.

All project files will be released under the terms of the BSD3 license after the first device was sucessfully build and tested.

Admin: Micha

ToDo

~~Building a prototype.~~ Done.
~~Relayouting the PCB to fix a few problems.~~ Done. - Below there is a section „problems“. If they are solved, the section should be reomved maybe?
~~Optaining components for the first few devices.~~ Done.
~~Documentation, sample project with Makefile etc.~~ Done.
~~Manufacturing~~ and testing the new (and probably final) version.
Debugging the device and/or fixin' the bootloader.

Features

ATmega8 (48/168/328 upgrade possible) microcontroller with 8kB flash, 1kB RAM, 512B EEPROM available,
V-USB directly to the microcontroller, allowing emulation of low-speed USB devices,
breadboard compatible (2.4„ × 0.925“).

Design goals

Single-sided,
as slim as possible to make it breadboard compatible,
only use of cheap and easy to get components,
programmable over USB and
fully manufacturable at shackspace.

Problems (to be solved)

A few clearances are too close. Shorts after manufacturing are almost unavoidable:

Hardware

Pin mapping

Layout diagram

Required components

Quantity	Component	Name	Value	Package	Price	Order number ¹⁾
1	ATmega8	IC1		TQFP	2.30€	ATMEGA 8-16 TQ
1	Crystal	Q1	16MHz	HC49	0.26€	16,0000-HC49-SMD
2	Ceramic capacitor	C1,C2	22pF	0603	0.10€	NPO-G0603 22P
1	Ceramic capacitor	C3	100n	0603	0.05€	X7R-G0603 100N
1	Electrolytic capacitor	C4	1µF		0.04€	SMD ELKO 1,0/50
1	LED	LED1		1206	0.10€	SMD-LED 1206 GN
2	Z-Diode	D1,D2	3.6V	SOT-23	0.10€	SMD ZD 3,6
1	Resistor	R1,R2	68Ω	0603	0.10€	SMD-0603 68
1	Resistor	R5	220Ω	0603	0.10€	SMD-0603 220
1	Resistor	R3	1.5kΩ	0603	0.10€	SMD-0603 1,5K
1	Resistor	R6	10kΩ	1206	0.10€	SMD 1/4W 10K
1	Resistor	R4	1MΩ	0603	0.10€	SMD-0603 1,0M
1	Tactical switch	S1		LSG	0.29€	TASTER 9313
1	USB-B Mini female connector	X1			0.24€	USB BWM SMD
2	1×12 Pinhead	JP1,JP2			0.14€	SL 1X36G 2,54
1	1×2 Pinhead	JP3				?
1	Epoxy PCB board				1.05€	EPCU 120×80
-	Time at shackspace				priceless
Total					5.17€

Software

Boot loader

bijouboard is best used with USBaspLoader. This is a boot loader which emulates USBasp, a USB based AVR programmer. To avoid a license conflict, a pre-configured version will separately be available.

The boot loader is quite easy to use. Set the 'Enable boot loader' jumper on the device, connect it to the host computer and (if not bus powered) issue a Reset on the AVR. You can now flash the device with AVRDUDE through a „virtual“ USBasp programmer.

Arduino IDE

In order to upload firmware from Arduino's IDE, the file 'hardware/arduino/boards.txt' in Arduino's main folder must be changed. Add the following lines at the end of the file:

##############################################################

bijouboard.name=bijouboard

bijouboard.upload.protocol=usbasp
bijouboard.upload.maximum_size=6336
bijouboard.upload.speed=19200

bijouboard.build.mcu=atmega8
bijouboard.build.f_cpu=16000000L
bijouboard.build.core=arduino

bijouboard.upload.disable_flushing=true

##############################################################

Comments

Using as USB-to-Serial_5V Adaptor?

Arduino compatible HW (without USB) sometimes has some 6 pin header for a „FTDI Basic breakout“ on it. I don't know how popular that pinout is, but I have that connector on the DIYGeigerCounter.

There are some ready-to-use USB cables with the 6pin on the other side, also some FTDI-boards with mini-usb to 6pin. But prices seem to be higher than this project and sometimes it is not easy to get.

It looks like this projects could be also used for this if there was just a female plug with the right pinout that fits on that 6pin header. As such stuff tends to be plugged rather often, a plug soldered to the pcb is preferrable over just using some lose wire with the plug.

Does adding 6 pins with the right pinout at the edge of the board sound like an interesting addition?

Plus one of course needs some USB-to-serial firmware on it that works with the usual OSes and e.g. the Arduino SW.

— Thomas Waldmann 2011/11/20 02:26

¹⁾

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