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Forum Index : Microcontroller and PC projects : Can the Durinomite handle this?
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lewist57 Newbie  Joined: 07/01/2014 Location: United StatesPosts: 6 |
New to forum and the durinomite, so bear with me. Questions: 1) It appears that the Durinomite firmware and supporting software is "in flux". I have never used the board before, but wanted to know that the board, its firmware and software are relatively bug free. The appeal of the board is its simplicity, low cost and native BASIC programming, but all of that goes out the window if the firmware or software is buggy. 2) I want to use a Durinomite to read a digital 0-5V square wave signal into a frequency counter, which then must be multiplied or divided to calculate and display a value via the I2C bus to a 4 line LCD display. Along with that, want to pick up a 0-5V analog signal that must be converted from analog to digital, which also must be displayed on the LCD display. I don't have a hard and fast time requirement, but I would like for all of this input, conversion, and display to cycle through in 1 second or less. With Durinomite running BASIC, is it "fast enough" to capture the one digital and one analog inputs, do the conversions, and update the LCD display in a 1 second cycle? |
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vegipete Guru  Joined: 29/01/2013 Location: CanadaPosts: 1110 |
Should be easy. How fast is the square wave? Visit Vegipete's *Mite Library for cool programs. |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
The latest version V4.4C is very stable and (almost) completely bug free. So I would use that. See my web pages for the download. If your input is below 200KHz then measuring its frequency is very easy. Just feed it into an input with counting capabilities, configure the input and read the frequency in Hz. Geoff. Geoff Graham - http://geoffg.net |
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| lewist57 Newbie Joined: 07/01/2014 Location: United StatesPosts: 6 |
Thanks for your input. The input frequency will be below 200 hz. Believe it or not, the input is from a doppler radar unit, and I want to be able to capture the digital output wave and a voltage to determine the distance of an object from the transceiver. The purpose is for use on a vehicle as a primative "blind spot" sensor to alert the driver of other vehicles around their vehicle. The 1 second cycle is arbitrary, but I just wanted assurance that between the processor speed, conversion time and use of BASIC that the unit would not be too slow to meet the 1 second limit. For the analog input, what is the resolution of the analog to digital conversion? 128 bits, 256 bits? |
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BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
I couldn't find a lower limit for frequency detection but the DM probably has to see a few cycles before it can produce a result. That may slow your processing if your input frequencies get very low. Quoting Wikipedia, Doppler radar is used to determine the relative difference in velocity between a source and an observer. You will have difficulty measuring the distance to an object with Doppler radar. I assume that is 128 or 256 points of resolution. The MMBasic manual states that an analogue input will report the measured voltage as a floating point number and further that numbers are stored and manipulated as single precision floating point numbers. The maximum number that can be represented is 3.40282347e+38 and the minimum is 1.17549435e-38. You are unlikely to need resolutions better than a millivolt so it would seem you are OK with that. If I recall correctly (and I may not), on the original Maximite (I don't know about the DM) the analogue inputs were limited to 3.3 volts. The limitation is the maximum input voltage on the processor pins that read voltage. This can be overcome by using a voltage divider on the input and scaling up the reading in your program. |
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| lewist57 Newbie Joined: 07/01/2014 Location: United StatesPosts: 6 |
Yes, your are correct that the Doppler type radar unit that I am working with outputs an "intermediate frequency" which is the difference in Hz between the original signal and the return signal. However, the amplitude of the output (the analog 0-5V signal) is related to the distance. The purpose of the system is simple: 1) Warn you that something is nearby, and 2) Give you a 'relative' indication if it is near or far away. There is no intent to make this an accurate measurement of distance, accuracy probably will never be better than +/- a couple of feet over 60 feet, but that suits my needs perfectly. |
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