I've got the media button strip from an old HP Pavilion http://www.laptop-guts.co.uk/images/HPD ... HSTRIP.jpg The buttons are capacitive touch buttons. There are 7 buttons and a 5 element capacitive slider (for volume control). I thought it would be very cool if I could figure out how to interface this so that it can be used in other projects. The problem is that the construction is chip-on-board type, and the chip is covered in epoxy, so I have no idea what chip is being used :-/
The PCB has got 'Synaptics' printed on it. The Synaptics website has no datasheets, but it does have a generic interface manual.
There is an FFC-like connector on the board with 12pins, out of which only 8 are connected.I've figured out which is ground (actually two pins are grounded - pins 7 - so that leaves 6 pins to figure out).
Another wire (pin 5) is connected through resistors to the anodes of all the illumination LEDs and it is the thickest trace on the board. Some of the LED cothodes are grounded. The LED cathodes on the slider and the 'mute' bi-colour LED go to the CoB chip. So this thickest trace seems like Vled.
After measuring the resistance from each of the pins to Gnd, one wire showed about 850ohm, reverse biased, and open circuit when forward biased with a DMM. This tells me that there's probably a reverse voltage clamping diode between this wire and Gnd (Diode forward voltage mode showed me 0.675v). Sounds like Vcc? This same pin (Pin 1) has got a series 22ohm resistor (yes 22, not 220 or 2.2k or anything else) leading to the chip. There is a capacitor on this to Gnd after the resistor. Could this be a reset with 22ohms and not Vcc? I'm assuming it is Vcc, with a small resistor to decouple power supply noise.
4 more pins: SPI? Or I2C with reset and interrupt. But how do I figure out which pin is which? All the 4 pins show a rapid increase in resistance and then open circuit when forward biased with a DMM (sort of like what happens when a small capacitor is charging up). When reverse biased, 2 pins (Pins 3 and 4) show a 1080ohm (actual diode voltage of 0.705v) and the other two pins (Pin 2 and 6) show 1160ohm (diode 0.725v).
I have a BP which I've used to toggle the pins. I connect what I think is Vcc (Pin 1)and Vled (Pin 5)to 3.3v. The illumination LEDs light up. Slider LEDs are off. Mute is orange. Taking one of the pins to a 'high' state turns the Mute LED blue. If this wire is left floating, the mute LEDs sometimes rapidly changes colour.
Sorry if this query seems so vague. Let me know if I can describe anything better.
I've attached at composite image of the board along with pins named. Sorry for the rubbish blending - Photoshop couldn't handle it so I quickly did it by hand.
Destate9 says: Is that a plastic zip tie on a heat sink? I guess something like that wouldn’t get too hot, but that still was the first thing that caught my attention
Comment from the main page. I found that a nice way to attach heatsinks is to use a tiny bit of cyanoacrylate adhesive (Feviquik/Quikfix, etc). Make sure that the heatsink and the top of the chip are not pitted and are clean, put a drop of cyano and whack the heatsink on. I've used this method pretty successfully with DIP L293D motor drivers. Of course, this is a 'permanent' type of solution, but is handy if the chip isn't going to dissipate a ridiculous amount of power.
I'm a PIC guy. :-) I occasionally use the Arduino to test out proof-of-concept type projects since there are so many libraries already available online. So yeah, TCPIP - here I come!
Damn, I've still not gotten round to messing about with TCP/IP, ethernet. But now maybe I will. I've got a couple of ENC28J60s lying about along with magnetics scavenged from an old PCI network card. Will try to rustle up something. That's a pretty nifty ethernet 'shield' you got hooked up. More info?
Cool! I'm thinking of throwing together a veroboard SMPS breakout for myself too. But isn't having no fuses is a bit dangerous for the SMPS, not to mention the circuits downstream? Farnell/Kits-n-Spares has got 2Amp TH PTCs available very cheap for Rs.12 (~20 cents). Maybe you could include them in your next order from them! :-)
The Mele A1000 seems kickass! Better specs than the VIA APC. Granted that the APC is USD50, but with shipping it'll go to about 80 bucks. AliExpress has the Mele for about $100 including shipping. 20 bucks more for better features? Not bad....
I'm really thinking of buying the MK802 for $65, and then picking up an APC when it becomes available.[/quote] Mine's already on the way from AliExpress :-) I will be using it primarily as an addition to my set top box. But I'm waiting for the VIA APC to release. That looks more hacker-type.
Hey everyone! This is an old-ish project of mine, but I was hoping to tweak it a bit (with your suggestions!) and spin myself a new one sometime.
The board was intitally developed for a workshop in my University for microcontroller noobs. We built more than 100 boards. The dev board was used to teach soldering as well as programming to the participants, so to keep things easy a lot of board components are TH. The MCP2200 and the LM1117-5 were pre soldered.
The board uses the Arduino philosophy of 'stackability' and easy connection, so all the pins are broken out to female box headers. Machine pin headers are used to connect single strand wire, since I found that the box headers didnt grip single strand wire too well. Additionally, even if a 'shield' is present on the board you still have access to all the pins. So you could use a shield and a solderless bread board at the same time. 5v, Gnd and Rx, Tx from the MCP2200 are also broken out seperately so you could potentially use this as a USB-TTLserial converter with other devices. The board has a jumper connected to the MCP's RTS pins, which allows ds30Loader to software reset the PIC. A removable jumper was necessary because the MCP interferes with the reset line during ICSP.
This is v3 of the board. I've got a few boards of earlier revisions that I populated and I frequently use when banging together a project. I've already made several 'shields', the most recent one being an programmable audio trigger for a DSLR my friend has. I've attached an image of the POV shield I made in action.
All files are CC-BY-SA. Feel free to make changes and improvements. Would love if you give me shout when you do. (Pins and functions on both the Top silk and bottom silk are named as per the 16F882/886. While the board can be used for other 28pin PICs, please verify if your PIC's power and Gnd pins are compatible with this board)
Yes, the link above will help you. You don't need to 'program' the PCD8544 'internally'. The Atmega8 'configures' the PCD8544 using a simple protocol. So all you need is an Atmel programmer, nothing else.
AndThen is right. The PCD8544 is called an LCD segment driver. A chip-on-glass (CoG) type construction is used to attach the PCD8544 to the display elements. You only need to use a microcontroller to provide control signals to the PCD8544, which then drives the appropriate pixels/segments on the LCD.
The boards look nice and really well laid out. Great job! You could start an eBay shop to sell the boards. But yes, 15 bucks a chip is pretty expensive. Maybe you could sell boards populated with all the passives and only leave the chip buying/sampling to the end-user.
Seeed/iTead definitely works out cheaper on all counts (and they include a solder mask as well as silkscreen). While temperature controlled irons are better, I have used plain-jane 20W irons on Seeed's boards without a problem on tracks which were 10mil. Noobs who had never used irons before managed to solder just fine. So I don't think its the iron (or the person soldering) who's responsible for tracks lifting in this case. The quality of the copper-to-substrate (FR4/epoxy) bond matters a lot. Sometimes even a little bit of heat can lift tracks. Therefore Seeed/iTead ftw.
