[William Dillon] is finishing up his degree. His final project as a student was to design an RF transceiver. He decided to work with the Microchip MRF49XA, which runs around $3 but will cost you $20 if you want it in a ready-to-use module. He didn’t find a lot of info on the Internet about communicating with these chips so he’s shared his design, code, and board files. If you’re ever wanted to delve into RF design this is a good primer. [William] talks about building around the example circuit from the datasheet but also includes a discussion of the calculations he made in working with the 434 MHz band, and an AVR-based library for using his module.

Ah, the heady aroma of damp engineers! It’s raining in Silicon Valley, where the 2010 Embedded Systems Conference is getting off the ground at San Jose’s McEnery Convention Center.

ESC is primarily an industry event. In the past there’s been some lighter fare such as Parallax, Inc. representing the hobbyist market and giant robot giraffes walking the expo. With the economy now turned sour, the show floor lately is just a bit smaller and the focus more businesslike. Still, nestled between components intended to sell by the millions and oscilloscopes costing more than some cars, one can still find a few nifty technology products well within the budget of most Hack a Day readers, along with a few good classic hacks and tech demos…

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It seems a bit late to the party, but Microchip has just announced a family of PIC development boards for Apple products. The three offerings include a digital audio development kit, 8-bit accessory development and charging kit, and a 16-bit accessory development and charging kit for iPhone or iPod.

We’ve seen a lot of homebrew Apple addons that use microcontrollers. This not only takes the hardware interface to the next level, it does it with Apple’s blessing. But somehow that doesn’t seem like quite as much fun.

[Thanks Juan]

[Colin Merkel] had a little problem: he was continually forgetting his electronic key card, locking himself out of his own dorm room. Like any normal Hack a Day reader, rather than getting in the habit of always carrying his card, the natural impulse of course is to build this elaborate rig of electronics and duct tape. Right?

The result is an additional keypad that can be used to gain access…not by altering the existing electronic lock, but with a secondary mechanism that operates the inside door handle. An 8-bit PIC microcontroller scans the outside keypad (connected by a thin ribbon cable), and when a correct access code is entered, engages a 12 volt DC motor to turn the handle. It’s a great little writeup that includes a parts list, source code, and explains the process of keypad scanning.

It’s similar to the RFID-based dorm hack we previously posted. By physically operating the handle, most any approach could be used: facial recognition, other biometrics, DDR pad, or whatever inspired lunacy you can dream up.

A few weeks ago we held a preorder for the Bus Pirate universal serial interface tool. We split the preorder into two parts due to a shortage of PIC 24FJ64GA002-I/SO chips. The first preorder is arriving worldwide now, the second preorder has a longer lead time. Here’s everything we currently know about preorder 2, it’s subject to change, but we wanted to keep you up to date.

Preorder 2 contains orders for 563 Bus Pirates. Seeed Studio noticed an error in our quality control testing routine that misclassified about 50 preorder 1 Bus Pirates as defective. We updated the test and passing units will ship immediately to preorder 2 participants on a first come, first serve basis. Another 500 PICs are scheduled to arrive after August 1, which should take care of most remaining orders.

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Microchip’s TC74 is an inexpensive digital temperature sensor with a simple I2C interface. It has a resolution of 1 degree Celsius, and a range of -40 to +125 degrees. This is an easy way to add temperature measurement to a project without an analog to digital converter. We’ll show you how to use the TC74 below.

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This mini web server is slightly smaller than a business card. There are a lot of tiny one-board servers out there, but this is probably the smallest you can etch and solder at home. Unlike many embedded web servers, files are stored on a PC-readable SD card, not in a difficult-to-write EEPROM. Read on for the web server design, or catch up on PIC 24F basics in the previous article: Web server on a business card (part 1).

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For years, Microchip PIC microcontrollers dominated; PIC16F84 hacks and projects are everywhere. The 8-bit 16F and 18F lines are supported by several coding environments and easy-to-build serial port programmers. Microchip’s 16-bit PIC24F is cheaper, faster, and easier to work with, but largely absent from hacks and projects.

We recently used a Microchip PIC24F microcontroller in a mini web server project, but didn’t find many introductory references to link to. In this article we’ll cover some PIC 24F basics: support circuitry and programming options. We’ll also talk about our favorite features, and how we figured them out. Our next article will outline a web server on a business card based on the PIC 24F.

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