Good news - we're open for limited services in Wembley. Ujima House is now actively under refurbishment and we'd love your help in making the space the best it can be.
During this interim period donations and continued membership are greatly appreciated while we transition to our new space.
This section added by Daveb who is looking for more info... see ATMEL's AVR and AVR32 - Quick Reference Guide for useful info.
ATTiny rather than an ATMEGA as it is smaller and lots cheaper or would use an arduino or similar. ATTiny rather than other MCUs for good free tool (GCC etc) support.
Doing searches on Farnell reveals lots of choices, with big price breaks (~40%) for 10 and (~20%) for 100. Price seems to roughly scale with pin count or maybe chip size.. but there are anomalies. It is worth picking a chip and buying a few. But how to choose the chip??
Points that matter to me..
- enough RAM for interrupt vectors, global state variables, C stack, local variables and interrupt stack
- excess code space for diagnostic code
- a few excess pins to allow for in-crcuit reprogramming and debugging (which i think means dont use MOSI,MISO,SCLK or RESET in the application)
An 8 pin dip has 2 pins available to the app (4 debug plus vcc and gnd), while a 14 pin dip has 8 app pins? Four times the app space for under 2x the size:)
in the farnell catalogue at moment i see some standouts.. These are all 8kflash, 512byte ram parts.
- Not in stock - ATTiny84A-PU 14 DIP, 1.8 to 5.5v, at upto 20Mhz, ADC with 1x, 20x prescale, £1.90(units), 1.39(10s), 1.28(100s)
- ATTiny 85-20PU 8 DIP, 2.7 to 5.5v, at upto 20 Mhz, £2.36(units), 1.36(10s), 1.14(100s)
- ATTiny861A-PU 20 DIP, 1.8 to 5.5v, upto 20Mhz, 3PWM, ADC with 1x, 8x, 20x and 32x prescaler :) £2.10, 1.72, 1.48
I like this prescaler, can see it simplifiying some designs.
The part that started my investigation - only 1k flash and 64bytes of ram - one 8 bit counter and no prescaler for the ADC.
- ATTiny13 8 pin DIP 2.7 to 5.5v, upto 20Mhz, £2.48(units), 1.55(10s), 1.13(100s)
- attiny13a 8 pin dip new version, 1.8v to 5.5v, upto 20Mhz, £2.48, 1.38(10s), 1.31(100s)
--- In stock now :)
- 1x attiny85-10pu 1.8v to 5.5v, 10MHz (after I took 1)
- 1x attiny13-20pu
- SRAM chip x 2
- Raspberry PI - to be available from Farnell... would be great to run hacking courses for these, as they are very affordable, and capable and low power (green)!
Please help by finding an appropriate link for the following.
- new tips for the general soldering irons! (Not at space so can't check models, if this matters)
- "brass sponge" for cleaning soldering iron tips.
- A couple of stiff brushes - to make cleanup around MIll and Lathe easier. Perhaps with some chain to tie them to the table.
- LEDs (varying, some good bright ones) +1 (we have loads of basic red/green/yellow etc ones)
- you can get LEDs dirt cheap off ebay. i bought 500 blue LEDs for under 7 quid a little while ago. if you want to go with a more reliable brand, green LEDs red LEDs blue LEDs bicolour LEDs found after a quick price check between rapid and RS. i haven't worked out how to use farnell's website yet so i can't comment on their prices.-alecjw
- 12V 3A solid-state relay
- solid-core cable (RGBYKW) and multicore
- http://www.rapidonline.com/Cables-Connectors/Equipment-Wire/Equipment-Wire/1-0.6mm-Single-core-equipment-wire-on-100m-reels/62317 seems to be the cheapest, having done a quick price check against RS and Farnell. I have 2 reels at home: orange and blue - can bring them in. -alecjw
Tools and equipment
See the Wishlist page.
Some tools we could regard as consumables; get cheap ones and replace them frequently. E.g.:
- screw drivers
Tool bits and pieces
Recently retired/thrown away
- spade-drills which had side of the spade drill broken sized 8, 10, 12 and 22 (2011/04)
- Down to the last hacksaw iron blade (2011/04) - 410 length
- Down to the last Pendulum Jigsaw saws of the non-T shape saws (2011/04)
We're running low on:
- Logic chips. I think the 74HCT series is a reasonable place to start, but I'm not an expert here.
- Some banaplugs or already wired up banaplug wires in the usual colours and length.
- dark blue multicore wire Akki14 06:57, 29 May 2012 (UTC)
- Heat shrink (bought some its on top of the component wall shelves - need more)
- Masking tape
- Header Pins - Order Code: 9729038  x 2
See also: Inventory#Stocked components.