Electronic Projects and DIY Solutions

Sous Vide Board - Troubleshooting a New Board

Details: Published: Thursday, 26 July 2012; Written by Jon Chandler

schematic-300 Powering up my new sous vide controller board required to troubleshooting to find an easily fixed problem. Some indications were misunderstood, resulting in some confusion. I'm sharing this systematic troubleshooting process to help you analyze problems.

The Board Design

The board is based around a 28-pin 18F-series micro and a TI TMP513 chip configured to read a thermocouple. The board has a 16x1 connector for a HD77480 character LCD, two inputs for switches and an output to control an SSR (solid state relay). In keeping with the TAP-28 convention, there are 6 pin connectors for I2C (the TMP-513 uses the I2C interface) and UART communications. The board was designed with general applications in mind, so there are also locations for an I2C EEPROM, a Microchip RTC and a MCP-23017 port expander chip.

Because of the number of port pins needed, the LCD data lines share the ICSP clock and data lines.

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DipTrace layout and ordering boards from Dorkbot aka OSH Park

Details: Published: Sunday, 22 July 2012; Written by Jon Chandler

From KuzyaTech

KuzyaTech has a gerat article on producing printed circuit boards at OSH Park using files generated by DipTrace. Following these recommendations will help ensure you get the boards you expect.

Well, my test design is complete and now I need a few prototypes to play with. The usual ways of ordering PCBs are rather expensive, with just tooling fees in hundreds of dollars. The remaining options are a few China based places, and an OSH Park ran by Laen from Dorkbot. He runs a community PCB service that groups orders and orders them periodically on a common panel, sharing costs between all people. The cost is very reasonable ($5 a square inch) and you get three boards. So a 2″ board in three copies will cost you $10 delivered. That definitely opens the door for quick prototyping of pretty much anything! After having used other company’s prototyping services, I must say OSH is also by far the most user friendly. Lets walk through the steps of ordering these boards.

First you need to check that the design complies with the design rules listed. Ideally those are setup at the beginning so that you do not have to deal with things being too close or two narrow after the fact. Here is what they look like in DipTrace (Under Verificaton, Design Rules)

Read the entire story

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DJ Hero Teardown

Details: Published: Thursday, 19 July 2012; Written by Jon Chandler

Game controllers are pretty sophisticated these days. If you've seen the DJ Hero controller, you may wonder how it works. There's a 45-RPM-record-sized turntable for "scratching" which rotates freely which includes 3 pushbutton switches on the rotating piece. Obviously, the turntable rotation is read with some kind of encoder but how the switches are read is a mystery. I recently came across one of these at the right price, so with screwdrivers at the ready, let's delve into the internals.

The platter rotates very freely. With a good spin, it will rotate at least 10 turns before it slows to a stop. There's no resistance from any mechanical linkage between the platter and the base. The "controller" snaps on to the side of the turntable part through a somewhat complex mechanical linkage with includes a 4 pin connector.

EEVblog #313 – Bus Pirate LCD Debugging

Details: Published: Tuesday, 17 July 2012; Written by Jon Chandler

EEVBlog-304 As MrDEB contemplates using another LCD, Dave Jones has created another great video on using Dangerous Protptype's Bus Private for testing an LCD display. I've mentioned the Bus Pirate here before - it'sa serial analyzer/interface that understands a number of protocols. If you're trying to figure out an I2C, SPI, UART or One-Wire interface (among others) the Bus Pirate can be a huge asset.

Dangerous Prototypes makes an 74HC595- based converter to go from the serial protocol that the Bus Pirate understands to the parallel interface of a character LCD. If this sounds at all familiar, it's a technique that been discussed by mrbasher and Mike here extensively in the past.

Dave makes quick work of checking out a 8x2 display with the Bus Pirate. As with most of Dave's videos, there are lessons to be learned, including the dangers of using dual-row header cables. Dave had a crossed cable between the Bus Pirate and the '595 adapter board which was quickly found and corrected. If the cable had been reversed between the '595 adapter and the LCD, the outcome mat have been much worse.

Dave is very good at systematic troubleshooting - watch and learn.

EEVblog #313 – Bus Pirate LCD Debugging

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