These kits are designed by companies such as Analog Devices, Cypress Semiconductor, Freescale,Fujitsu,Infineon,Maxim,Microchip Technology, STMicroelectronics, Texas Instruments and more. A good way to get a data sheet, pricing and order parts is to use the web site of a major distributor such as Digi-Key (look at “ToolsXpress”) or Mouser (“Embedded Solutions”).
Figure 1 shows the block diagram of an embedded media module from Arcturus Networks Inc. This particular module allows a design engineer to create a product that would incorporate a wide range of two way voice, broadcast audio, mini-PBX or video.
It has connections for a variety of serial data busses that can be used for control of devices or for data transfer. These include CAN, USB, UART, SPI and SDIO. Each type of microcontroller kit will have its own application orientation and features but a common element will be the availablity of a variety of serial data ports.
Testing the Development Kit
Much of the testing when developing a product that incorporates a microcontroller development kit involves sending control instructions and data via the serial busses. Simple tests may be to send a single control word and check to see if the desired action occurs. More complicated tests might be to send an instruction to the microcontroller via one buss, then look for the MCU to issue commands to devices on a different buss and prehaps send/receive data via a third buss. Substantial engineering development/test time can be used in verifying proper operation of the microcontroller and the various devices to which it is connected.
In order to speed the product development process, vendors of digital oscilloscopes can provide optional packages which can trigger, decode and in some cases even graph the contents of serial data messages. Figure 2 shows an example in which channel1 of an oscilloscope has been set up to trigger if a data value of “4c” (hexadecimal) is seen on an SPI buss.
Note in the lower right corner the Trigger box says “Serial SPI”. The timebase is 200 usec/div and the vertical scale for channel 1 (C1) is one volt/div. The upper trace shows both the voltage versus time signal, as is normally seen on an oscilloscope, and the decoding of the serial data stream. The trigger time for the upper grid is indicated by a yellow triangle just below the grid. It is easy to see the trigger time comes just after the data packet that had a value of 4c. If the design engineer wanted to see what happened before or after the “4c” value arrived on the SPI bus, additional probes could be hooked up to other serial data lines or to any other points of interest either on the MCU or other devices.
The second trace in Figure 2 is shown on the lower grid. This one is from an I2 C bus. It is a zoomed detail of a waveform that was previously captured and is being held in the memory of the oscilloscope. The trace is labeled Z1 (it is a zoom of the information in memory M1) and the trace descriptor box at the bottom of the scope screen shows the data is being displayed at 200usec/div horizontally and 1 V/div vertically. For the acquisition of this data the oscilloscope was set to trigger on an I2C address of “5c” (hexadecimal) if the data packets following that address also contained a value of “4c”. The trigger time for this acquisition is indicated by the yellow triangle below the lower trace (just after the “4c” value). Using this kind of technique an engineer can capture an event, save it in memory, capture another event and then compare the two. Or, depending on the type of oscilloscope used, the instrument can capture 4 such signals simultaneously along with up to 36 digital lines from a variety of address and data lines.
Summary
Some osciloscopes can be loaded with a variety of optional packages that can trigger, decode and graph the data from many types of serial data busses. These oscillscopes are very useful in the design and testing of products based around microcontroller development kits.
