Search found 408 matches

by UhClem
Wed Sep 27, 2017 8:46 am
Forum: Projects
Topic: MPU9250 schematics
Replies: 1
Views: 204

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: 2530

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: 379

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: 379

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: 685

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: 256

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: 440

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: 504

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: 786

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: 816

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 ...
by UhClem
Tue Feb 09, 2016 10:29 am
Forum: SparkFun Product Questions
Topic: Arduino mini frying Mosfets
Replies: 15
Views: 816

Re: Arduino mini frying Mosfets

Regardless of what you think that circuit is doing, it cannot work. 5V from the Arduino cannot change the state of the P-channel MOSFET. Sure it can. Those two FETs are connected exactly the same way as a typical CMOS inverter. The common drains are either pulled up or down depending on the input. ...
by UhClem
Tue Feb 09, 2016 9:40 am
Forum: SparkFun Product Questions
Topic: Sunny Buddy fault light
Replies: 6
Views: 351

Re: Sunny Buddy fault light

dsegel wrote:The Sunny Buddy is connected to a Large Solar Cell (PRT-07840) and a 6Ah LiPo battery (PRT-08484)
What is the open circuit voltage of the PRT-07840?
What is the voltage of the PRT-08484?
by UhClem
Thu Nov 05, 2015 4:25 pm
Forum: SparkFun Product Questions
Topic: Accelerometer long wires problem
Replies: 13
Views: 451

Re: Accelerometer long wires problem

Very strange. Stray capacitance in very long connections could be an issue, but I can't imagine why 2 feet would be a problem. I would think that inductance would be the problem. I see that the board has a capacitor on the power supply so that is probably OK. But it wouldn't take a lot of inductanc...
by UhClem
Wed Aug 26, 2015 5:53 pm
Forum: Projects
Topic: Analog Datalogger "Logomatic" Problems
Replies: 19
Views: 679

Re: Analog Datalogger "Logomatic" Problems

andrewfed wrote: are you saying i would be able to sample the data im looking for on the v1 with your code ?
I am saying that both the V1 and V2 hardware is up to the task with the right firmware.
by UhClem
Tue Aug 25, 2015 1:29 pm
Forum: Projects
Topic: Analog Datalogger "Logomatic" Problems
Replies: 19
Views: 679

Re: Analog Datalogger "Logomatic" Problems

it looks like this project may be more along the lines of what im doing http://www.blog.exrockets.com/blog/simple-diy-pic-micro-data-logger-with-sd-card-and-4ch-12b-adc/ That device is slower than the Logomatic and always will be. Even with better software because the PIC18 was insufficient memory ...