The software identified the 1-Wire reset command, and the 1-Wire ‘search rom’ command (0xf0). We also tried the 1-Wire decoder with a DS2431 EEPROM. This transaction shows the host issue the read configuration register command (0x05), and the SRAM response (0x41). Without it, you’d have to count clock pulses to identify byte boundaries, and then manually decode the values. Profiles suggest names for each signal, and convert squiggly lines into readable byte values. CAN and other protocols will be added eventually.
We really like the profiles that decode most common serial protocols 1-Wire, I2C, SPI, and asynchronous serial. We set the Logic trigger to start sampling when SPI enable is 0 by changing its trigger to ‘0’. Since we’re analyzing SPI, the most logical place to start capturing is when the SPI enable signal drops at the beginning of a bus transaction. There’s a four level trigger that watches the signals, and waits for a specific combination before it starts recording samples.
The total number of samples is limited only by the available PC RAM. A 24MHz sampling rate can capture signals up to 12MHz, we found this suitable for all the protocols we use. We were able to sample at 24MHz, but the top speed depends on how much other stuff is using the USB bus. The primary configuration options are the sampling rate (200KHz-24MHz) and number of samples (millions to billions). The software analyzes and displays signal captures.
Comments on SparkFun’s product page suggest that reversing the connections will damage the Logic. We associate a black wire with ground, but the Logic cable uses gray. The E-Z-Hooks make it dead simple to tap into the signals without accidental shorts.īe mindful of wire orientation. SPI has four important signals enable, data in, data out, and clock. We connected it to the 32K SPI SRAM that we demonstrated earlier this week. Connect the gray ground wire to the ground of the test circuit, then hook into the signal lines you want to record.
NET 3.5, download the redistributable off-line installer if you don’t want to give internet access to Microsoft’s online installer. Right now, only Windows XP/Vista software is available, but Mac and Linux software should be ready soon. We always download the latest software, so we appreciate that there’s one less CD headed to the landfill. Software isn’t included, instead you get instructions to download the latest version from the Saleae web site. The retractable tweezers prevent accidental shorts on cramped test circuits. The hooks are a really nice touch press the back of the hook to expose a pair of tweezers, grab onto a signal wire, and retract to hold it in place. A mini-B USB cable is included.Ī heavy-gauge cable and nine E-Z-Hooks (5 shown) connect the Logic to a circuit. It’s much smaller than we expected, slightly smaller than a compact flash storage card. The analyzer is a small, anodized aluminum puck with laser etched signal markers.
The Logic comes packaged in an external hard drive case. Logic analyzers dump data to a computer for analysis, very few oscilloscopes have this feature. A logic analyzer only detects high and low digital states, but it records many signals simultaneously. An oscilloscope displays a graph of an analog voltage as it varies over time, such as the curve of a sine wave. Most modern electronics projects will benefit more from a logic analyzer than an oscilloscope. It’s now widely available, and Saleae gave us one to try. When it debuted, the Logic was so popular that it was hard to buy one. If you’ve ever considered bringing a product to market, you can learn a lot from Joe’s blog that documents his development process. We’ve been following Joe Garrison’s work on the Logic for a long time. Among hobby-level logic analyzers, the Logic has a good mix of features and decent sampling rates. The Logic is a USB logic analyzer with eight channels and sampling rates up to 24MHz. 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. A logic analyzer records bus communications between two chips.