Fundamental Logic is selling a Bus Pirate kit and bare PCB based on our universal serial interface tool. They started with our serial port-based v1a hardware, and modified it to use all through-hole parts. 8pin DIP LP2951ACN/-3.3 switchable voltage regulators replace the surface mount TPS79650/33 that we used. The PIC is pre-programmed with our latest firmware, version 0f, which includes a bootloader for easy firmware updates through the serial port. Documentation includes illustrated assembly instructions.
Speaking of Bus Pirate goodness, we’re busy working on hardware V2. As astute readers may have already noticed, the final version of the Bus Pirate incorporates an FTDI USB->serial chip, and draws its power from the USB port. We also tackled the software-controlled pull-up resistor feature, and reduced the overall part count and cost. Best of all, we’re working to make assembled PCBs available with world-wide shipping. The how-to should be ready in a few weeks.
Microchip’s MCP6S21/2/6/8 are programmable gain amplifiers that multiply an input voltage by a factor of 1, 2, 4, 5, 8, 10, 16, and 32. The MCP6S22/6/8 also have selectable input channels for working with different signal sources. The multiplication factor and input channel are configured through an SPI interface. This chip is useful for multiplying a small input signal, and selecting among several analog input sources. We demonstrate the six channel MCP6S26 below.
Continue reading “Parts: Programmable gain amplifier (MCP6S26)”
We’re putting a bounty on two high-priority Bus Pirate features. You can get a free PCB for the upcoming Bus Pirate V2 by writing a bit of code. Hack a Day has a varied and talented group of readers, and we know someone out there has the experience to make these changes with minimal difficulty.
- The latest code integrates the PIC24F bootloader for easy updates without a programmer. We’d like to add a protocol snooper, but that requires interrupts. With the bootloader, however, interrupts are relocated and we’ve yet to fully grasp how that works. We’ll send a PCB and PIC 24F to the first person who modifies the code to demonstrate UART, SPI, or change notification interrupts with the boot loader. Microchip’s 24F bootloader app note is available here. Complete.
- The current frequency measurement feature is a hack that uses a counter and a timer. Be the first to implement the input capture peripheral instead, and get a free PCB. See the function bpFreq(void) in base.c. Complete.
The latest Bus Pirate code and compiled firmware can be checked-out from Google Code SVN. Submit your code via the comments below or firstname.lastname@example.org.
UPDATE: Both issues were resolved. Thanks for your suggestions.
Dallas/Maxim’s DS1801 is an audio volume potentiometer with a simple SPI interface. This chip has two channels of volume control that might be useful in a DIY audio project. We previously looked at the DS1807, a similar part with an I2C interface. This week we’ll show you how to use the SPI version.
Continue reading “Parts: DS1801 SPI audio volume potentiometer”
We covered SparkFun’s new RGB button pad controller a few weeks ago. This is a full-color clone of the monome interface; a 4×4 grid of buttons with tri-color LEDs underneath. Each LED has 24bits of color control, for more than 16million color combinations. Up to 10 panels can be chained together to create huge button grids, like SparkFun’s Tetris table. We previously used a smaller version in our RGB combination lock.
We asked SparkFun to send us the SPI version of the button controller to test. This is a new product developed in-house at SparkFun, with open source hardware and software. Read about our experience interfacing this board below.
Continue reading “Parts: 4×4 RGB button pad controller SPI”
A logic analyzer records bus communications between two chips. If you’ve ever had a problem getting two chips to talk, or wanted to reverse engineer a protocol, a logic analyzer is the tool you need to spy on the bus.
The Logic is a USB logic analyzer with eight channels and sampling rates up to 24MHz. Among hobby-level logic analyzers, the Logic has a good mix of features and decent sampling rates. We’ve been following Joe Garrison’s work on the Logic for a long time. If you’ve ever considered bringing a product to market, you can learn a lot from Joe’s blog that documents his development process.
When it debuted, the Logic was so popular that it was hard to buy one. It’s now widely available, and Saleae gave us one to try. Read our review below.
Continue reading “Tools: Saleae Logic, logic analyzer”
Microchip’s new 23K256 is a serially interfaced 32 kilobyte SRAM memory chip, available in 8 pin DIP and 8 pin SO packages. SRAM, like EEPROM, is a data storage medium. Data stored in SRAM is lost without constant power, but it’s really fast and there’s no limits to the number of write cycles. EERPOM stores data even without power, but it’s slow and usually limited to around a million write cycles.
32K SRAM chips typically have 15 address lines and 8 data lines, like the IS61LV256AL we used on our CPLD development board. The 23K256 requires just four signal lines, but sacrifices the speed of a parallel memory interface. It’s a great way to add extra memory to a low-pin count microcontroller without routing 23 signal traces. We’ll show you how to interface this chip below.
Continue reading “Parts: 32KB SPI SRAM memory (23K256)”