The purpose of technical documentation is to precisely convey information to other people who possess the technical skills needed to apply it.  It is not to pass along technical skills, although reading technical documentation on a system designed by someone more experienced often will.  It is not to explain a system to management to enable their decision-making processes, that need is properly met by the inclusion of executive summaries and project plans in software specifications alongside

Or sink. Whatever. No matter which word you use, there's a need for the logic to source a current of 25mA (or reasonably close). I definitely prefer LED banks with anodes tied to the positive power rail. NPN and NFET transistors are more efficient per unit area than their PNP or PFET counterparts, so interfacing LEDs usually can be done using microcontroller GPIO pins to sink the current (but be sure to check the rated sink current, the ADuC7025 makes no promises of more than 1.6mA ), and a series

Strictly speaking, the EPCS main function of toggling valves at set intervals doesn't require any user input, and it's likely to be quite some time before an algorithm is embedded to provide real-time results, so a display is also not necessary, but a device without a user interface is an inflexible one. The development and debugging process will also be greatly eased by an integrated display. I did some looking around on Digi-Key for a small inexpensive LCD panel , but what impressed me

As previously mentioned , the EPCS will take advantage of the FTDI FT2232H USB-serial converter and its integrated multi-protocol synchronous serial engine (MPSSE) support for JTAG for programming and debugging the ADuC7025 firmware. The second serial port provided by the FT2232H will be used in UART mode to provide a link for streaming data back to a PC. I envision two uses of this UART: The UART communicates via a RS-232 level converter and standard DB-9 connector to act as a generic USB-serial

Having a microcontroller in an embedded project doesn't do much good until you are able to program it, because in contrast to fixed-function ICs or configurable ICs with reasonable defaults, microcontrollers have little to no useful behavior from the factory. Some families of microcontroller, like the Z-World Rabbit or Microchip PIC , have unique programming circuits so your choice of programmer is essentially made for you -- you buy the adapter available from the IC vendor for several hundred

While writing the post on selection of the microcontroller , I got a little deeper into the capabilities of the integrated ADC peripheral. Initially I had just been relying on past experience with Analog Devices ICs for assurance that if the basic specs were sufficient then my needs would be met. But now I've discovered that the ADuC7025 ADC provides adjustable scaling and common-mode rejection , which are two functions currently delegated to the AD8227 instrumentation amp s. Yet I have a number

A while back one of the embedded design newsletters I receive mentioned a kind of "super-ADC", barely more expensive than the usual ADC and about the same size but with a microcontroller embedded (for example, the ST7FOX , S08QD , AVR ATtiny25 , and P89LPC90x are all 8 pins, while the AVR ATtiny10 has 4 ADC channels in only 6 pins), allowing for programmable digital filters right on the front end. Think 50/60Hz notch filters to take out noise caused by fluorescent lights (the power grid

Since the whole purpose of the EPCS is to mitigate the need for a human to turn two stopcocks twice per minute, we need to replace the stopcocks with electric control and that means an solenoid pneumatic valve. The arrangement of the stopcocks was such that one port needed to communicate with either of two pressure reservoirs, thus a single 3-way valve is sufficient. I started googling for suitable valves and found lots of options in the $100 price range -- $100 to replace a 50¢ piece of plastic

We now interrupt our regularly scheduled engineering to bring you an example of how NOT to lower expectations:   But they must not have thought they were winning the brag-on-your-product competition, because the reverse side of the box steps up to bat AGAIN:   I'm going to finish this post with my old keyboard just in case the new one refuses to process the word "HUMILITY".

Blood pressure is one of the better known vital signs, measured by just about everyone, often with a non-invasive blood pressure cuff. But the cuff is inaccurate, yields only one measurement per cycle (approximately 60 seconds) and causes tissue damage if inflated too often, so for critically ill patients and in animal experiments blood pressure is recorded continually using an invasive arterial line. This is simply a catheter placed into an accessible artery, such as the radial artery, and connected