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One thing to note is that outputs 24 to 33 requires you to solder the outputs directly to the solder pads. I'm not exactly sure how you intend to mount the board, but if you are using a breadboard for your prototyping, it may be quite a squeeze with a mass of wires running out from underneath...

Constantin, thanks for your insights. I don't really need a 0.05% accuracy for my application, simply becoz I did not use higher precision components in my circuits (particularly, the resistors were 1% rated). But I found your comment regarding the sampling time rather interesting. Are you able...

I'm fairly curious how you intend to multiplex 18 voltage sources into a single channel. You mentioned something about transistors. Won't you need 18 outputs to individually control them?

I'm sorry if I confused you, there are two issues here. Firstly, there is noise in successive sampling on any single channel (let's say I use A0 and successively sample a single voltage source, say 1.5V. In my case, I was using a NiMH battery. Yes, it is not exactly the most stable voltage...

I have done a fair bit of experimentation with the ADC on Teensy 3 previously: http://forum.pjrc.com/threads/15718-Interesting-observation-on-the-ADC-of-Teensy-3-0 Bottom line, the ADC values are approximately 4 ADC units apart at 12 bit sampling. I am using a 2.5V external Vref (TL1431). I'm...

I did something similar but my motivation was on keyboard remapping instead of scripts. You can also see pictures on my implementation (post #20) as well for sharing some ideas. Cheers! http://forum.colemak.com/viewtopic.php?id=1561

LarryP, thank you for your insightful post, I will give the idea of throwing away the initial readings a try.

Hi, browsing around the forums and the K20 reference manual, I came across this ADC calibration stated in para 31.4.6. Can anyone explain to me what it does and how can we do this calibration using the registers in Teensyduino? Also, would I expect better ADC accuracy after calibration? Thanks!

Paul, the readings are coming from a circuit that I have been building from my other thread. It is basically one of the terminals on a sense resistor which the other terminal is grounded. The current flowing through this is controlled via a n-channel MOSFET which is turned off. So theoretically...

Can someone explain to me what analogReadAveraging does? I seem to have better noise rejection using analogReadAveraging versus a manual averaging, i.e. the results from the following pseudo codes are not the same analogReadAveraging(16); analogRead(A0); versus analogReadAveraging(1); for...

I find the learning curve for Eagle to be too steep and I intend to use Fritzing to create my first PCB (home etched!). If you would be so kind as to convert it to a Fritzing part (I actually don't really care so much for the breadboard, I only need the schematic and PCB view), that would be...

Did you set the timer prior to first use? Teensy3Clock.set(atime_t) You can get the current epoch time from here: http://www.epochconverter.com/

Thanks Paul!

Can someone tell me what is the baseline PWM frequency in Teensy 3 using analogRead? Thanks! Also, has the beta code for analogReadFrequency been incorporated into the latest beta11 for the Teensyduino?

Paul, I consider this issue closed. Basically, as Jp3141 pointed out, I did not include a capacitor of at least 10uF to stabilise the TL1431. The inclusion of either a 33uF or 100uF capacitor (of which I happen to have on hand) solved the oscillation problem. Jp3141, just to give closure to this...

This is the results from Teensy 10 bits: A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 552 0 0 0 0 0 0 4 0 0 0 553 34 7 12 24 10 14 58 31 5 3 554 6466 881 1204 2946 2013 1913 8591 4393 1073 1640 555 211560 68158 72838 121360 99432 88197 230714 163874 67512 107588 556 426702 442136 435664 441671 443433 436505...

This is the output from Leonardo. The ADC values was only 555 and 556 with zeros in all other ADC values, very clean! A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 555 5232 5275 5258 5314 5332 5323 5120 5165 5173 5185 556 301 258 275 219 201 210 413 368 360 348 To be fair, this is 10 bits compared to the...

I got both good and bad news. The good news is, using a 33uF or 100uF works! It solves the oscillating problem and provided a stable reference. Now the bad news, it seems like there is still some inherent characteristics across each of the channels. I have tried reading from A0 to A9, then A9...

Thanks Jp3141. I missed out that chart in the datasheet completely! :p In the datasheet, the x-axis is in mF and not uF. I hope it's a printing error on the datasheet as 0.1 uF is way way to the left of the charts. In fact, it seems that 100 uF will be smacked right in the centre of the...

Lol, I'm sure something is wrong that's why I'm asking for help. :o You are right in that logically, the voltage cannot be lower than what I started with (be it 3.3V or 2.5V). However, I'm completely baffled as to the results that I'm seeing. Sorry for probing more info but where should I be...

Jp3141, thank you for staying with me on this thread. Your explanation on the shunt is very clear, now I understand how the currents are flowing in my circuit. On my specific implementation, with the 5V Vcc connected to the TL1431 through the 330 ohm, the output was 2.50V (as expected). The...

I tried to do a search on the teensy codes and found that choosing DEFAULT and EXTERNAL actually makes no difference to the code (they have the same #define codes). For the TL1431, all I did was to tie REF, cathode and AREF all to the same pin. Anode is connected directly to ground. Vcc (5.12V...

Thanks guys for the input. I have tried to wired up a shunt regulator and ended up with more problems than I started. Hope to get some advice. I took out my Teensy and soldered a single core wire to the AREF pin. I also fashioned up a DIP board to hook up a TL1431. Using a voltmeter to measure...

Results with 3ms delay between all reads. 1701 0 0 0 1 0 0 0 1 0 0 1702 2 0 1 0 0 2 0 6 1 2 1703 19 2 3 5 5 6 18 37 2 1 1704 119 25 52 88 32 39 178 263 12 55 1705 641 163 212 480 249 285 864 1339 106 407 1706 2649 818 1005 1711 1217 1513 3938 5184 764 1957 1707 9547 2999 3348 6038 4533 6626...

This is the result of swapping the read sequence from A9 backwards to A0. A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 1702 0 0 0 0 0 0 0 3 0 1 1703 1 0 0 0 0 2 0 4 0 5 1704 4 0 0 4 0 1 4 42 3 81 1705 5 3 6 18 4 4 57 327 32 573 1706 67 11 47 79 22 57 487 1609 324 2611 1707 421 123 261 474 307 567 2345 5302...

Nantonos, I couldn't believe it but when I swapped the reading sequence around, indeed now A9 has a higher reading than A0. I'm still generating data as I'm typing this (around 30k data points). I probably would be able to post some results in an hour's time or so (intending to generate at least...

Hi, I'm trying to design a smart discharger for my batteries in order to determine their capacity and automatically shut off the discharge when the batteries go below a certain voltage. In my course of preparing the software and hardware, I realised a very interesting phenomenon across the...