Recent Posts

91
General Discussion / Re: where is TinyTV IR receiver?
« Last post by lennevia on January 04, 2021, 01:44:52 PM »
Hello,

The IR Receiver is located at the top of the TinyTV on the MicroSD and Audio TinyShield. Looking at the picture on the product page, it would be the black square at the bottom of the board: https://tinycircuits.com/collections/audio/products/microsd_audio-tinyshield

When installed in the TinyTV, the chip is at the top of the TV case.

You could try using a fresh battery in the Tiny Remote, but since the enclosure blocks the receiver, you may only get around 12" of reach with the Remote at that point.

I hope that helps!

Thanks,
Réna
92
Hi, I have an Arduino MKR1000 working with a lithium-ion rechargeable battery pack  (7.4V) in a toy car. I need the 7.4V so I can power the Arduino and the other peripherals attached to it. I would like to place the car on a charging plate to wirelessly recharge.  I plan to get the induction charging coils. Is there any hardware from TinyCircuits that I can use to help me achieve this setup? Will greatly appreciate any guidance. I am open to switching to NiMH batteries if that makes it simpler.

I noticed this charger (link below) but it is for 4.2V, not sufficient for an Arduino. Is there a 7.4V version?
https://tinycircuits.com/products/tiny-battery-charger?_pos=1&_sid=9df44ebf1&_ss=r

93
General Discussion / where is TinyTV IR receiver?
« Last post by mcdandm on January 02, 2021, 02:04:44 PM »
I received a TinyTV kit for xmas and got it all assembled and working  except the TinyTV only responds to the remote if I aim it directly down the microUSB port in the top. Is this normal or have i blocked access to the receiver somehow?

Thanks
94
TinyDuino / Re: TinyZero Smartwatch Screen stops working
« Last post by lennevia on December 30, 2020, 06:21:24 PM »
Have you tried the original example for the TinyScreen from the getting started tutorial? https://learn.tinycircuits.com/Display/TinyScreen_TinyShield_Tutorial/
95
General Discussion / ZOE GPS proto board in 35 mm model rocket application / Results
« Last post by WillemH on December 30, 2020, 05:33:05 AM »
This last post on the ZOE GPS proto board in a small 35 mm rocket application deals with the main results of launch trials of the MER-35-ZOE model rocket.

Two launches of this rocket were executed on 9 November 2020 at Laren (Gld.), The Netherlands.
Weather was excellent for launching.

For an overview and detailed figures see the attached presentation.

Given the used Klima C6-5 rocket motor with a specified peak thrust of 15 N and a total rocket mass of 130 + 21.5 ~ 152 g it is clear that the acceleration limit of 4G in the dynamic platform model of the ZOE-M8B will be exceeded at least for a short time interval during the boost phase.
It depends on the model estimates inside the ZOE if this will be detected resulting in missing position fixes or not.
 
Main results

Herewith some main values for launch #1 resp. launch #2, see also slide 9 of the attachment:

-   Maximum forward acceleration (corrected for gravitation): 10.2 G, 10.0 G
-   Average forward acceleration during boost phase: 4.4 G, 3.9 G
-   Maximum altitude (above ground level / barometric): 135 m, 134 m
-   Maximum altitude (above ground level / GNSS): 134 m, 134 m
-   Trajectory length (by double integration of forward acceleration): 146 m, 135 m
-   Trajectory length (GNSS, step by step): 146 m, 137 m

The maximum forward accelerations are somewhat higher than expected (~9 G).

Average forward acceleration at launch #1 was higher than that of #2 resulting in max vertical velocities of 54 m/s and 49 m/s respectively. However, max altitudes were nearly the same (135 and 134 m). Launch #2 was more vertically oriented leading to a much smaller difference between trajectory length and altitude as was also visible on site and on videos.

Model rocket trajectories

The different trajectories can be visualized by the following figure, in which GNSS longitude (x), latitude (y) and altitude (z) are depicted relative to launch point:
 

(Figure 1, see attachment, sheet 11)

Launch #2 is much more vertically oriented as can also be seen from rotated versions of this figure (see attachment). In the trajectory of launch #1 six position fixes are missing, presumably because of too high forward acceleration, “too much > 4G”.

Altitude and other measurements

Altitudes (corrected for ground level at launch) measured by both barometers and GNSS are rather close to each other as can be seen in the next figure for launch #1. Correction for time alignment was not necessary.


(Figure 2, see attachment, sheet 15)

The barometric altitudes have a more noisy character. It would help a bit to take the average of the outputs of the two barometers or to use more averaging per barometer.

The GNSS altitude curve is rather smooth, but it is striking that the altitude after touchdown is more negative than the height of the launch platform. So the GNSS altitude also includes some random walk effect.

The two barometric outliers relate to measured pressure peaks (so altitude dips) during ejection of the nose cone section including parachute.

For figures showing forward acceleration and roll rotation please refer to the attachment.

Because of the canted fins which are designed for a roll rate of 2000 deg/s (~5.6 Hz) at a forward velocity of 40 m/s, it is expected to see the roll rate increase with increasing forward velocity. This is indeed the case.
Also note that the LSM9DS1 gyro output saturates just above 2000 deg/s conform specification.
This happens in fact at ~6.4 Hz.
Magnetic field attitude readings are used to fill in the saturated gyro part.

Conclusions

It has been shown that the ZOE GPS prototype board can be successfully applied in a small 35 mm diameter model rocket.

ZOE setup modification through UART only took some effort, but proved to be done in a reliable way.

The trials were successful with 5Hz GNSS and ~50 Hz sensor data.

The ZOE-M8B gave six missing position fix data during the boost phase of launch #1, the one with the higher forward acceleration.

As next step it is planned to implement “Enable position output for invalid fixes” using the UBX-CFG-NMEA command in the ZOE setup in order to avoid missing position fix data in follow-up trials.


Regards,

Willem
96
TinyDuino / Re: TinyZero Smartwatch Screen stops working
« Last post by dreckbot on December 29, 2020, 07:28:35 PM »
I also had this problem. The watch screen worked for some time but stopped working completely. I went through the same steps to test the connection to my computer and the ability to load the correct sketches. The screen still blinks when I press the buttons but the screen will not display. It has been an amount of time since I originally bought the kit so, I'd be fine with buying another.
97
General Discussion / Re: ZOE GPS proto board / ZOE setup with examples
« Last post by jgavlik on December 21, 2020, 05:18:24 PM »
Ben,

How can one charge the battery if the UART (USB port, I assume) is being used for this board? Let me know if I'm off base on this.

BTW, a 20mm x 20mm board would be fantastic!

Thanks,
John
98
General Discussion / Re: ZOE GPS proto board / ZOE setup with examples
« Last post by Ben Rose on December 18, 2020, 06:04:46 PM »
Thanks for the feedback, really appreciate it. Based on this and some review here, I think we will try to make this a 20x20mm TinyShield compatible with all processor boards, and use the ZOE-M8Q with UART as well as I2C if I can route it. The origins of the TinyScreen+ format board were a pretty specific use case. I'll update here, we'll build a few extra prototypes.
99
TinyDuino / Re: TinyZero with Accelerometer & Wake from Sleep
« Last post by HunterHykes on December 18, 2020, 03:05:33 PM »
Hi Steve,

As can be seen in the TinyZero schematic and board files, the INT1 pin of the BMA250 accelerometer is only broken out to a solder pad on the bottom side of the board. This is the small copper circle labeled "INT1" next to the "BOOT" button.

Because of this, a wire would have to be soldered to this pad and then input to the processor via a Proto Board TinyShield. According to the official Arduino documentation for interrupts, any digital pin except for digital pin 4 is usable for interrupt input to the TinyZero processor.

If this is something you'd still like to pursue, I can look into getting some sample code for this.

Hope this helps.
- Hunter
100
TinyDuino / TinyZero with Accelerometer & Wake from Sleep
« Last post by SteveDorr on December 17, 2020, 01:14:24 PM »
Hi,
I just purchased a Tiny Zero with the built-in accelerometer.  I would like to build a small app that goes into low-power mode and wakes up via an interrupt from the accelerometer if it detects significant movement.

I have the accelerometer working, but I'm looking for some sample code which puts it to sleep and codes the accelerometer to generate the interrupt appropriately.  From what I read people were soldering connections to make INT1 work on the proto board, but I'm wondering about the TinyZero which has it all integrated on the same board.

Thanks for your help.
Steve
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