Audiovisual Learning Device

I’m building an audiovisual learning device with a target price of $15 per unit. This would be a talking book of sorts, for rapidly teaching English to students in developing countries. We found that we couldn’t give enough attention to one child, and that they would learn faster if they were free to learn at their own pace.

The modules used:

• SPFD5408 based 2.4 TFT + 4 wire touch + SPI SD slot ($3.50)
• MCP4921 12 bit DAC ($1)
• MicroSD Card ($2.5)

The DAC may be removed in a later edition by using a STM32 microcontroller with built in DAC.

The current status is getting the components to work on arduino and reading the Arduino libraries for the above modules. Then I guess I’ll be able to port it with some help from the internet.

Notes:
SPFD5408 is compatible with ILI9325 library called Adafruit TFTLCD, with only minor changes to the library. So I’m hoping that Andy Brown’s tutorials on ILI9325 driver for STM32 will help out in writing this as well.

Resources:

• SPFD5408 library https://github.com/JoaoLopesF/SPFD5408
• Arduino Wave Shield that uses MCP4921 https://learn.adafruit.com/adafruit-wav … o/download
• Andy’s Workshop ILI9325 driver http://andybrown.me.uk/2012/01/01/stm32 … ft-driver/

I would love the input of the community, especially on alternative modules, or any tips. I’m especially looking for the best way to present a UI on the TFT. Current plan is to use a ported version of Adaruit_GFX library, but are there better options out there for STM32? Maybe a graphics library with interchangeable TFT driver?

Looks like an interesting project, when you say “talking book of sorts”, how much content is on the device?

From the description, presume the device will read phrases and present images from a storage medium (SD card?)

How do you envisage the device being powered?

How rugged do you expect it to be? Kids in rural India are no different from kids everywhere, intentionally or not, they are very good at breaking things

Where are you based, and how do you intend to distribute/sell these devices?

How do you envisage creating the content?

What language does your target audience speak, and how will you QA the translations?

I’m sorry it wasn’t clearer. Most of the content will be printed matter, in order to provide a richer visual experience at that low price.

Yes, an SD card will store any multimedia. I forgot to mention it, but the LCD shield I’m using has an SD card interface via SPI (updated the post).

Good question about power: Li-ion and a charger would work, right? Or perhaps it could use Ni-Mh batteries (AA shaped) for easy swapping.

In regards to ruggedness, I see it as being self contained and relatively waterproof. However, it would have to be extensively field tested. The circuitry will be modular of course, with the control board, LCD board and audio being separate.

I’m currently based in Assam, India, and I’m currently counting on the help of the Indian government for R&D and launch once it’s time to scale. However while in initial development I’m open to the option of having students of our university participate in the project at all levels (coding/engineering as well as translation and content creation).

I already have meetings lined up for when a prototype is ready.

iwalpola wrote:
<…>
Good question about power: Li-ion and a charger would work, right? Or perhaps it could use Ni-Mh batteries (AA shaped) for easy swapping.
<…>

You may want to consider using an STM32F103RC MCU, as this has on board DAC.
This saves the cost of the external but the F103RC is more expensive, by about the same amount.

However the F103RC also has other features which the C8 doesn’t have, so for the extra cost you get things in addition to the DAC, including more ram
See

http://htmlpreview.github.io/?https://g … tList.html

Also using the larger MCU gives you the option to swap to a F103RE, which has even more ram and more flash.

I am sure that you will be a able to build something that works, but I am not sure you will be able to make it for under $15, especially when you start to factor the cost of the rugged enclosure, and batteries, and method to charge it e.g possibly solar.

I suspect the price point would be possible if you get the volumes, however it would need to be pretty well engineered, in terms of both best bang for buck, and robustness and the volumes would need to be fairly high. After all, in a word where you can get a bluetooth enabled smart watch for <15$, then this project certainly sounds possible.

No doubt one or two of you (iwalpola included perhaps) have been watching this …
https://www.theguardian.com/technology/ … -this-week
… looks like it might actually exist after all. Android + Display + battery for $4… or thereabouts.

ahull wrote:No doubt one or two of you (iwalpola included perhaps) have been watching this …
https://www.theguardian.com/technology/ … -this-week
… looks like it might actually exist after all. Android + Display + battery for $4… or thereabouts.

RogerClark wrote:I would love to be able to by a $5 RPi Zero, but they dont exist in the wild either;-)

Thanks Rick,

I suspect that the price they charge will need to go up by 15% to match the drop in the value of the pound. So there wont be any real saving by buying products from UK vendors who do not manufacture in the UK.

I am also not sure of the shipping charges to me, but perhaps they have a flat rate.

I was also, just pointing out, that the RPi zero is supposed to be a $5 product, but in practical terms you cant buy them.

It would be better to have a $25 product that you can buy, rather than a $5 that you cant

Hey, guys !
Why are you in love with RPi-Zero ?
You can get OrangePi-One for $9 and it still have ETH port.
Of course, the form factor is a bit bigger, but it is worth compare to RPi-Zero.

martinayotte wrote:Hey, guys !
Why are you in love with RPi-Zero ?
You can get OrangePi-One for $9 and it still have ETH port.
Of course, the form factor is a bit bigger, but it is worth compare to RPi-Zero.

Yes, but OrangePi-One is also smaller than original Pi, about half of it, but not on the height side, but on the width side.
https://linux-sunxi.org/Xunlong_Orange_Pi_One

EDIT: But I think the BestValue is OrangePi-PC+, which I still didn’t received it yet, same as PC but with eMMC 8MB along with onboard WiFi.
https://linux-sunxi.org/File:Orange_Pi_PC_Plus_top.jpg

Thanks Martin,

I think I’ll add it to my Christmas list

Christmas is a bit far …
… or maybe you means “Summer Christmas” as we say here in NorthPole

Ah, Good point. Perhaps I should mean Christmas in July

https://en.wikipedia.org/wiki/Christmas_in_July

In Quebec here, there are some folks that says in french “Noël des campeurs” …
In fact, it almost collide with the beginning of the summer as well a National Holidays (Yes ! 2 in rows ! one for Quebec followed by Cabada).

This thread is going way off topic

@RogerClark Thanks for the tip about STM32 series, I didn’t pay attention to the MCU peripherals when I bought the board. Getting it to $15 will be fairly tough, but it’s worth a try.

@andy yeah I had a hard time believing the “Freedom 251” when I first heard about it. This company had been caught with unethical practices such as reselling another brand’s phone (at a loss), but I guess they were faking it till they made it. I’m fairly skeptical still, but who knows? And why $4? If the phone could really be sold for that amount, why didn’t they add a margin of at least 50% and raise some money for more R&D? It’s a starting-out company after all. They’re going to ship soon, so we shall see. I’ll get one and do a teardown if possible.

iwalpola wrote:This thread is going way off topic

mrburnette wrote:iwalpola wrote:
<…>
Good question about power: Li-ion and a charger would work, right? Or perhaps it could use Ni-Mh batteries (AA shaped) for easy swapping.
<…>

martinayotte wrote:iwalpola wrote:This thread is going way off topic

Maybe it can be useful the jpeg decoder library written by rowboteer
http://forum.arduino.cc/index.php?topic=376768
https://github.com/Bodmer/JPEGDecoder
It works on STM32 with little modifications
viewtopic.php?f=3&t=901&p=10745

iwalpola wrote:
…
Thank you for the tip, and after some googling I found that LiFePO4s aren’t that expensive, so it may be a great choice. And about charging, a solar charging station in the kids’ classroom may be a more reliable solution, something that is becoming affordable in India.

ahull wrote:
<…>
A 10W or greater panel would probably be required to consistently charge a mobile phone sized device even on dull days. I know India is generally considerably sunnier, (particularly Delhi today, apparently according to my wife who is visiting some of her relatives there at the moment, rather too hot, and rather too humid), but you do need to be aware that to charge a full classroom’s worth of devices might actually require more power than you think.