Search found 413 matches

by UhClem
Wed Jul 25, 2018 7:35 pm
Forum: Projects
Topic: Trouble with a Transducer - Trying to switch it off
Replies: 8
Views: 162

Re: Trouble with a Transducer - Trying to switch it off

That image is not nearly as useful as an actual schematic. For example, what is the sensor part number? I looked up the part number shown and that is a 5VDC part. The circuitry inside the sensor will not disconnect from its positive supply just because you removed its ground connection. So it could ...
by UhClem
Fri Jun 15, 2018 1:35 pm
Forum: Projects
Topic: Rocket accelerometer
Replies: 13
Views: 337

Re: Rocket accelerometer

i need to collect the acceleration's DATAs as well, so i must use three axis. the kalman filter will help to detect apogee ( the sensor detect the burnout ) so why would it be wasted? The extra two axis will pick up vibration and not much else. So unless you are trying to measure that, it is a wast...
by UhClem
Thu Jun 07, 2018 7:40 pm
Forum: Projects
Topic: Rocket accelerometer
Replies: 13
Views: 337

Re: Rocket accelerometer

I think you would want both, to more accurately measure the two acceleration regimes. If you use one then scale factor (slope) errors do not matter since you start at zero velocity and end at zero. But if you use one accel under thrust and a different accel near apoge, their scale factor errors mat...
by UhClem
Thu Jun 07, 2018 6:41 pm
Forum: Projects
Topic: Rocket accelerometer
Replies: 13
Views: 337

Re: Rocket accelerometer

@UhClem: Don't you agree that for apogee detection, one would want to use a +/- 2g (or similar) accelerometer? Absolutely not. What you are doing is integrating the acceleration and waiting for the velocity to go from positive to negative. I still have a BlackSky AltAcc2 which uses an ADXL50 accel ...
by UhClem
Thu Jun 07, 2018 10:20 am
Forum: Projects
Topic: Rocket accelerometer
Replies: 13
Views: 337

Re: Rocket accelerometer

If the only purpose is determining apogee, then one axis is all you need.

If the only sensor is the accel then the Kalman filter is wasted.
by UhClem
Wed Sep 27, 2017 8:46 am
Forum: Projects
Topic: MPU9250 schematics
Replies: 1
Views: 277

Re: MPU9250 schematics

falaroce wrote:Our CS# pin is connected directly to VCC, Does the lack of a pullup resistor could be the problem?
No. See Figure 2 in the MPU-9250 data sheet.
by UhClem
Sat May 13, 2017 3:57 am
Forum: MSP Microcontrollers
Topic: The 430F5529 Programming Troubles
Replies: 2
Views: 3844

Re: The 430F5529 Programming Troubles

I am not sure what the problem is but some comments: Why are you bit banging SPI when that chip has multiple SPI hardware ports? Your delay routine will get optimized to nothing. I don't know about your specific compiler but look for something like delay_cycles() for reliable spin delays. Or use a t...
by UhClem
Sun Apr 30, 2017 4:54 pm
Forum: SparkFun Product Questions
Topic: need Bright LEDs visible in daylight
Replies: 3
Views: 487

Re: need Bright LEDs visible in daylight

A quick search at Mouser showed amber T1-3/4 LEDs in stock with up to 21,000mcd output. So I don't know what your trouble is. Unless you want a diffused LED in which case the ratings are lower. You may prefer the diffused LEDs because of their wider viewing angle. I don't have a good handle on conve...
by UhClem
Sun Apr 30, 2017 11:27 am
Forum: SparkFun Product Questions
Topic: need Bright LEDs visible in daylight
Replies: 3
Views: 487

Re: need Bright LEDs visible in daylight

LEDs bright enough to be visible in daylight, at currents less than 20mA, have been around for a couple of decades now. All you need to do is pick one from among the many choices. Use the part sorting features at a vendor like DIgi-Key of Mouser to find what you need. As an example, I used PN SSL-LX...
by UhClem
Thu Mar 02, 2017 6:19 am
Forum: SparkFun Product Questions
Topic: BME280 lacks precision
Replies: 7
Views: 922

Re: BME280 lacks precision

The altitude reading is off by roughly double ( I'm at 136 meters, and the card logs 300+ meters). I suspect a correction factor needs to be included in the code to correct to sea level. Conversion from pressure to altitude is non-linear and subject to problems. Number one being that it assumes a s...
by UhClem
Tue Feb 28, 2017 3:38 pm
Forum: SparkFun Product Questions
Topic: Accessing Micro SD card data through SPI on Logomatic V2
Replies: 1
Views: 343

Re: Accessing Micro SD card data through SPI on Logomatic V2

There is just so much wrong with this, starting with connecting two SPI masters together. What you want to do is connect a micro-SD card socket to the Arduino.
by UhClem
Sun Dec 11, 2016 3:36 am
Forum: Projects
Topic: 12 v high side switch - need advice
Replies: 2
Views: 508

Re: 12 v high side switch - need advice

It doesn't matter if you use a BJT or a MOSFET, you must use two transistors because of the level shift required by the difference between the MCU output voltage and the voltage being switched. A quick Google search on "high side switch circuit" would turn up plenty of examples.
by UhClem
Wed Aug 31, 2016 3:21 pm
Forum: SparkFun Product Questions
Topic: MPU-9250 IMU with SPI
Replies: 1
Views: 622

Re: MPU-9250 IMU with SPI

I hooked up the MPU-9250 Sparkfun breakout on the Teensy 3.2 using SPI, but the WHO-AM-I register is incorrectly returning zero. Does the breakout board need any special treatment, like desoldering one of the jumpers or anything else? The schematic shows it as being configured for I2C and the SDO/M...
by UhClem
Mon Aug 01, 2016 4:10 pm
Forum: SparkFun Product Questions
Topic: Voltage Drop on MOSFET
Replies: 5
Views: 961

Re: Voltage Drop on MOSFET

It seems likely that you are using this as a high side switch without a high side driver. An N channel MOSFET will be on if the gate voltage is greater than the source voltage by its threshold voltage. So if you connect the drain to +5V the source will never be higher than +5V minus the threshold vo...
by UhClem
Tue Feb 09, 2016 11:54 am
Forum: SparkFun Product Questions
Topic: Arduino mini frying Mosfets
Replies: 15
Views: 990

Re: Arduino mini frying Mosfets

No, it can't. The P-MOSFET won't be turned off until the gate voltage approaches 12 V. Perhaps I am making an unwarranted assumption about the value of Vdd. (An actual value on the schematic would be nice.) I assumed it was 5V but maybe not. In any case the PFET is a waste of space because at best ...