This article from Wikipedia gives us a very comprehensive list of Arduino UNO compatible boards from “known” vendors.  There are 37 of them, excluding all the clones that are cheaply available from aliexpress etc. What makes Maker UNO distinctive is that it is specially redesigned for educational market. Let see what are the features / changes from the official Arduino UNO, follow the typical rules of “the good”, “the bad”, and “the ugly”

The Good

• More More LEDs. We all love LEDs. “Blinky” is probably the first Arduino project for many of us, then followed by “Chasing Lights”. Remember the tedious work to break out digital pins onto breadboard, plug LEDs and current limiting resistors? All these are no longer necessary with Maker UNO. We now have LED indicators built right onto the board for all digital pins. Imaging the amount of classroom time it saves! Even for advanced users, the LEDs can be super handy when debugging code. For example, turn on/off LEDs when “Serial.print” is not available, e.g., in an interrupt service routine.

• Buzzer and Button. Nothing is more exciting than making noise in the classroom. With Maker UNO it is now possible without additional hardware. A buzzer is built-in. If continuously making noise is not too welcomed in a classroom, then let the noise triggered by user button forms a more socially responsible project. Yes the button is also included. Of course there is also a switch that can turn off the buzzer permanently.

  

• Power option. Remember the gigantic 5.5mm DC jack and USB type B receptacle on the original Arduino UNO? Those are replaced by one single USB Micro-B port. Who does not carry a micro-USB cable now a days?

Summarize for the Good: More built-in peripherals, easier to power. All these significantly reduced the ownership cost and save precious classroom time.

The Bad

• I cannot really fault the board except for one issue: the CH340G USB-Serial chip it used. Well frankly speaking it is a bit unfair because I had not encountered one single problem with this chip. But historically CH340G had some issues with Mac OSX and it is largely due to the driver. So Mac users need to pay attention to download the correct driver. It is puzzling that the official WCH driver download page lists CH340G OSX driver as CH341.
  For Windows (Windows 10) users, driver is downloaded automatically from Windows Update hence no problem what-so-ever.

  

The Ugly

• Without reservation, I do have one complain. Look at the “GND” silkscreen label below. It seems as though the bottom three pins are all “GND”s because the bottom two pins are not labeled. But in fact the bottom most pin is VIN in official Arduino and “5VOUT” in Maker UNO. During one test I erroneously clipped the ground clip of my scope probe onto that pin, and BOOM, my USB hub turn itself off. So my board is a per-production version, I hope these pins can be properly labeled.

  

The Clever

Something went beyond “The Good” level. Lets save the best for last. And the best things are not always how good the construction is, how comprehensive the features are. For this time, the award belongs to the designer who made all the effort to include a blank space at back of the board for student to write his/her name! Who the genius designed this must have tons of experience in classroom! And my ultimate respect!

So here I finished my short review. Don’t forget to read the excellent article by Ober at https://hackaday.io/project/79748-arduino-uno-for-education, detailing the story behind Maker UNO. And see you Mar 23 2018 at KickStarter.

The post Arduino Redesigned – Maker UNO Review appeared first on Digital Me.

Wish you a very Merry Christmas.

VFDuino, Arduino compatible Vacuum Fluorescent Display module. Open source release imminent.

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Being not too much dedicated to Arduino, I have to quickly put up something demo-able. And since I’ve been playing with display devices often, I decided to make an Arduino graphics project. After two weeks, I finished my first Arduino game — FlappyDuino (thanks SG Makers William Hooi for inventing the name).

The project hardware is really simple. It only contains an Arduino Pro Mini, a ST7735 SPI TFT panel and a distance sensor (Sharp GP2Y0A21YK0F, which I used before in Project Crystal). I have put the KiCAD schematic, PCB and Arduino sketch code at https://github.com/baoshi/FlappyDuino. Feel free to download and criticise my code.

Lazy me also think a video is worth thousands of words.

Happy Birthday Arduino!

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Make the story straight. The Atmel ISP connector combines SPI bus and RESET signal. SPI is used for downloading program, and RESET implements Atmel’s “debugWire” on-chip debug system. debugWire OCD is a very fancy protocol that uses only one RESET pin to debug. ATmega328p supports debugWire, and hence the ISP connector on Arduino UNO can be used for debugging. Arduino Micro uses a newer ATmega32U4 chip. Surprisingly debugWire is missing from the product datasheet, instead JTAG is listed. JTAG uses 4 I/O pins,  from Arduino Micro schematic we can see the JTAG pins (TDI/TDO/TMS/TCK) are multiplexed with analog pin A0-A3. It appears I have to sacrifice these analog pins for the JTAG interface.

JTAGICE3 comes with a 10-pin JTAG header, with the definition as follows:

All I need to do is to make an adapter connecting these pins:

The actual construction is done on a perf board. I made it Arduino “Shield” type so they can be simply stacked together.

I admit it looks quite dangerous when stacked up

I hook up JTAGICE3 and choose JTAG interface in Atmel Studio. And no surprise. Murphy gets me everytime! “[ERROR] No JTAG devices detected.” is the only reply I get. I Scratch my head several hours then to realize how stupid I were. Since the pins PF4-PF7 have been used as analog inputs for Arduino, how can JTAG establish connection with these pins! And the resolution is simple: connect using ISP header and enable the JTAGEN fuse bit. Now I feel the usefulness of ISP connector.

I can finally talk to ATmega32U4 using JTAG and do some debugging. The coming year will be interesting

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This is the second year of the event and the venue was relocated from the remote (to me) Science Center to Singapore’s busiest Orchard area. And it is free entry for all

If anything would dominate the theme of the whole faire, that is 3D printer. This year we see less MakerBots, more self-built devices.

The huge printer “B.O.B” by romscraj (http://romscraj.com). Its gigantic metal frame makes every other printer looks like a toy. But it is not printing by the time I reach there. Printing huge object will take a long while, I guess…

An unfinished wooden 3D printer (mill? laser cutter?) silently sits beside a MakerBot Replactor 2, but certainly catches more attention. The wood framework is as sturdy as it looks. The booth is within the Sustainable Living Lab (SL2) platform, nobody was there at the moment, pity

This is the first time I saw the “Rostock Delta 3D” driving mechanism. Watching the three step motors running mad to keep the extrude platform flat == nerd porn.

Singapore Academy of Young Engineers & Scientists (SAYES, wonderful name) brought us ultrasonic water purifier. It (supposedly) uses high power ultrasonic wave to break dusts. The water in the photo may not look clear at the moment but half minute before a handful bunch of sands were just dropped in. BTW it effectively cleaned by glasses as well

Mood indicator by Media Lab LASALLE. It aggregates twitter messages and trying to detect sender’s mood by indexing keywords. A map is then plotted showing the mood of the people around the world. Is Singapore the world’s unhappiest nation?

Temperature recorder by the same Lab. It has integrated temperature sensor (of course), a GPS module and a dial letting people to choose if they feel cold/cool/perfect/warm. The data are then aggregated to map the temperature across the island. Very practical crowd sourcing application.

This Soundscape application (available on Andriod Market) creates 3D sound effects. Its bigger speaker brother (to the left side, sorry for the truncating) further demonstrates highly directional capability, definitely great for public events so the neighbours can stop complaining. These young startups has a website http://www.immersivesoundscape.com/ Please do checkout their cool inventions.

You will never see shortage of Arduino on a Maker Faire. This Email prank thingy contains an Arduino and a WiFi shield. It sends out an automated email when the button is pressed. May I have email notification when my coffee is ready?

Talking about coffee, these two coffee machines brew super strong coffee without electricity or hot watermark. Everything back to nature (future?).

This piano staircase leads up to the stage. But the sound is too weak to attract much attentions. How about a 100W Class-D Amp next time?

For the Arduino community 3E gadgets has brought in the little lovely TinyDuino board. Within the tiny 20x20mm square a full Adruino Pro Mini (ATMega328P/8Mhz) equivalent circuit is setup. There are also bunch of tiny shields available so user will have no difficulty to deal with the miniature connector. Another good news to the Makers here in Singapore is that 3E Gadgets is now an official distributor of Adafruit Industries. That means we do not need to pay the $8 mailing fee and wait extended days to get hands onto Adafruit products!

This is the second year I met Mr Jolyon Caplin. He is demonstrating a remote controlled toy excavator. With his modification this $80 toy almost became a robot dancer!

And as usual his signature light rods. Talking about the circuit, it is powered by an old school PIC16F84 (still available in Simlim Tower :-o) Getting most out of a chip is definitely the art of electronics design.

If Ian of Dangerousprototypes is the celebrity last year, this year we have Bunnie Huang. He gave a talk “Singapore better than United States for hardware makers”. Full report of his talk is here.

I shall end this post by introducing this wonderful lady engineer Michelle and her projects at AIS CUBE.

With a team of 2 they managed to implement a BASIC virtual machine inside PIC32 micro controller, together will a full development platform named “Sonata”. This is a tremendous meaningful project that opens the door for kids to learn electronics. I would compare it with the Raspberry Pi project, but this is much more low level yet easier to hand on.

And yes I’m the lucky bastard who grabbed one of these tiny twik^2 dev boards. At first glance it contains a PIC32 MCU, a 3 axis accelerometer  and a tiny RGB OLED screen (which is nice!) Please expect more to come about this little board.

Final words:

The maker movement definitely increases the talent pool. It is true even in a crowded island like Singapore where everyone is busy making ends meet. I hope those who sitting high above can hear it. Instead of bring talent in, why not incubate own talents? (quote from Bennie)

PS: No Raspberry Pi this year, why?

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I ordered several LED voltmeters from a taobao seller. It costs RMB16 each, about US$2.6 excluding shipping. The original design was for battery measurement on scooters. The advertised accuracy is 0.2%, which turns on my bullshit detector immediately. So the first thing I did after receiving it, was “don’t turn it on, tear it apart”. The manufacture did not scratch off the markings so the schematic can be easily traced out.

The heart of the voltmeter is “STM8S003F3P6”, a 8-bit MCU with 16MHz clock and 8K flash by STMicroelectronics. Datasheet shows this MCU has built-in 10-bit ADC. Driving 4 digits 10000 counts with 10-bit ADC is definitely overrating. While somebody may argue that ADC resolution can be increased using oversampling, without proper noise injection circuitry I cannot confirm it actually works. Furthermore the MCU does not have a dedicated ADC reference input. Supply voltage is used as reference. As the display needs to scan each digit continuously, supply fluctuation is inevitable. How to maintain ADC accuracy with changing reference? The original designer may have considered this problem initially. He/She added D9 (TL431 2.5V reference) and connected its output to analog input AIN6. So before measuring the input voltage at AIN5, 2.5V at AIN6 can be measured and then AIN5 calculated relatively. However D9 was not populated on the board I receive.

I was in the verge of desolder the LED and suddenly an idea bumped into me: why not reprogram this module and use it as a sole display? By doing so I can offload the LED driving task to the STM8. The original designer has reserved footprint for a 6-pin connector with SWIM programming/debugging interface and TX/RX serial port, reprogram should not be too difficult. A second thought is that it would be even better if I can emulate a popular serial LED module so that all existing codes can be used. The “Adafruit 4-digit 7-segment LED backpack” is soon identified. Ladyada did some remarkable work to develop Arduino library and wrote a tutorial for it. Make something compatible with her work is my honor.

However the Adafruit LED backpack is using I2C interface. The hardware I2C pins on the voltmeter is already occupied for driving LED, which means I need to bit banging I2C slave protocol on GPIO pins. There are many online resources about I2C master emulation, but I2C slave emulation is very limited. The best one I found is an article published by TI “Software I2C Slave Using the MSP430“. It depicts an entire state-driven process of interpreting I2C signals, together with some assembly code for MSP430. To help understanding I made a flowchart, and  rewrote the library using C code. As I’m not planning to explain the detail of the process here, all codes and documentation can be found at https://github.com/baoshi/I2C-LED

Some notes to potential users:

1. The code is compiled using “IAR Embedded Workbench for STMicroelectronics STM8”. The “KickStarter” edition is free (but needs registration) and limited to 8K code size, just nice for STM8S003F3.
2. The library is written in C. The efficiency is not as good as assembly code. As a result, at full 16Mhz clock and best optimization, I’m only able to archive maximum I2C clock of 63KHz, conservatively I use 50KHz clock during testing.
3. I tried the COSMIC compiler but the efficiency seems to be worse.
4. To change I2C clock in Arduino environment, edit TWI_FREQ variable in <arduino>librariesWireutilitytwi.h, or follow the great article by Nick Gammon.
5. STM8s does not support per-pin interrupt configuration, which is really pain-in-the-xxxx. Simulate the interrupt mode cost a lot of CPU time and hence is directly responsible for the slow I2C clock support. Migrate to a better MCU platform should give better result. But if you can change a MCU, why not use hardware I2C directly?
6. I2C reading is not implemented. The LED display is write-only.
7. Adafruit’s LED backpack uses Holtek HT16K33. All HT16K33 display modes are emulated, but not keyboard scan functions. Anyway Adafruit’s LED backpack does not have keyboard interface either.
8. Averaging current consumption (at 3.3V) is about 2.6mA, which is larger than HT16K33’s 1-2mA.
9. Developing and debugging this library is not possible without Bus Pirate’s 2Wire mode. Using 2Wire mode I can clock each bit individually so as to trace the I2C state.
10. Other than lower cost, there is nothing better than the Adafruit’s LED backpack. I did it because I can.
11. Hardware modification is shown in the picture below. Only the MCU, two resistor network and some bypass capacitors are needed.

All source code, schematic (in KiCad format), documents are available at https://github.com/baoshi/I2C-LED

The post Hacking a cheap LED voltmeter appeared first on Digital Me.

During my recent OLED testing I wrote the software using Arduino Pro Mini 3.3 – the only Arduino board with 3.3V I/O (Lilipad may be the other one but not breadboard friendly). Originally I was using the SPI interface and everything works fine. But when I’m trying to test the I2C interface I suddenly realize the I2C lines are not on the breadboard pins! Instead they are on top of the board and I have to use jumper wires to connect them, not as neat as I would like ;p

Looking into my inventory I found an Arduino Nano with all the necessary pins. But it uses 5V I/O only. So how to modify an Arduino Nano to 3.3V?  Adafruit already has a tutorial about it. But judging from the photos the modification is on a Uno. Uno uses different USB chip from Nano’s FT232RL, and hence we need some more steps.

So here is what we need:

1. Arduino Nano (of course)
2. A 3.3V regulator in SOT-223 package. Please note the official Nano design uses UA78M05 regulator, which has a different pin configuration than the popular LM1117-3.3. The one I found compatible is Micrel’s MIC37100-3.3WS, Digikey link here.
3. An Atmel ISP programmer, such as AVR JTAGICE mkII, or usbasp, or even a second Arduino as ISP.
4. A good magnifier!

Schematic below is the official Arduino Nano design with necessary modifications marked in red:

1. Replace the original voltage regulator.
2. Locate D1 from the board, cut the trace at cathode side and connect cathode to VIN of the regulator. Alternatively you can also remove D1 completely, but by doing so the Nano board is unable to be powered from USB, You’ll need to provide your own source voltage from Pin 1.
3. Cut the trace at FT232RL pin 4 (VCCIO), and connect pin 4 to pin 17 (3V3OUT). This enables FT232RL to use 3.3V logic.
4. Cut the trace at FT232RL pin 20 (VCC) and connect pin 20 to D1 anode (VUSB).

I would suggest to trace your board carefully before doing step 3 and 4. In my case the board is a Chinese enhanced modified version and all the power pins are connected by vias under FT232RL. So I had to desolder the whole chip to break the links. Just to share my modified board:

Till here the hardware modification is done.

However, if you carefully read the 660-page ATmega328 datasheet (which you should), at the bottom of first page:

Yes the chip is only specified at 10MHz with 3.3V supply. So unless you want to overclock your 3.3V Arduino at 16MHz, you should try to reduce the clock frequency.

Although the simplest way to modify clock frequency is to replace the 16MHz crystal with a 8MHz one, I’m out of luck because my board is using a tiny resonate instead of standard HC-49S crystal.

So the other way is modify the Arduino bootloader, configure CLKPR register to divide the clock by 2. To do this, follow the steps below:

1. Go to “c:arduino-1.0.3hardwarearduinobootloaders”, make a copy of “atmega” folder, I name my new folder “atmegad2”
2. Inside “atmegad2”, edit “ATmegaBOOT_168.c”, look for the main() function and add the following
   [code language=”cpp”]
   uint16_t w;

   #ifdef CLKDIV2
   // Disable interrupts
   ch = SREG;
   cli();
   // Enable clock change
   CLKPR = _BV(CLKPCE);
   // Change clock division
   CLKPR = 0x1;
   // Enough time for new clock to be stable?
   asm volatile(
   "nop nt"
   "nop nt"
   "nop nt"
   "nop nt"
   );
   SREG = ch;
   #endif

   #ifdef WATCHDOG_MODS
   …
   [/code]

3. Edit “Makefile”, add a new build target (I added right below “atmega328_pro8_isp: isp”)
   [code]
   atmega328_pro16div2: TARGET = atmega328_pro_16MHz_Div2
   atmega328_pro16div2: MCU_TARGET = atmega328p
   atmega328_pro16div2: CFLAGS += ‘-DMAX_TIME_COUNT=F_CPU>>4’ ‘-DNUM_LED_FLASHES=1’ -DBAUD_RATE=57600 -DDOUBLE_SPEED -DCLKDIV2
   atmega328_pro16div2: AVR_FREQ = 8000000L
   atmega328_pro16div2: LDSECTION = –section-start=.text=0x7800
   atmega328_pro16div2: $(PROGRAM)_atmega328_pro_16MHzDiv2.hex
   [/code]
4. Create a batch file “env.bat”, content below. This is to set correct building environment for the boot loader. You do not need a separate installation of WinAVR as the current version of WinAVR has some definition problem with Arduino bootloader source. The WinAVR within Arduino distribution is just fine.
   [code]
   set path=c:arduino-1.0.3hardwaretoolsavrbin;c:Appsarduino-1.0.3hardwaretoolsavrutilsbin;%PATH%
   [/code]
5. Open a command prompt, cd into “c:arduino-1.0.3hardwarearduinobootloadersatmegad2”, execute the follow:
   [code]
   c:arduino-1.0.3hardwarearduinobootloadersatmegad2>env.bat
   ……..
   c:arduino-1.0.3hardwarearduinobootloadersatmegad2>make atmega328_pro16div2
   avr-gcc -g -Wall -O2 -mmcu=atmega328p -DF_CPU=8000000L ‘-DMAX_TIME_COUNT=F_CPU>>4’ ‘-DNUM_LED_FLASHES=1’ -DBAUD_RATE=57600 -DDOUBLE_SPEED -DCLKDIV2 -c -o ATmegaBOOT_168.o ATmegaBOOT_168.c
   avr-gcc -g -Wall -O2 -mmcu=atmega328p -DF_CPU=8000000L ‘-DMAX_TIME_COUNT=F_CPU>>4’ ‘-DNUM_LED_FLASHES=1’ -DBAUD_RATE=57600 -DDOUBLE_SPEED -DCLKDIV2 -Wl,–section-start=.text=0x7800 -o ATmegaBOOT_168_atmega328_pro_16MHzDiv2.elf ATmegaBOOT_168.o
   avr-objcopy -j .text -j .data -O ihex ATmegaBOOT_168_atmega328_pro_16MHzDiv2.elf ATmegaBOOT_168_atmega328_pro_16MHzDiv2.hex
   rm ATmegaBOOT_168_atmega328_pro_16MHzDiv2.elf ATmegaBOOT_168.o

   c:arduino-1.0.3hardwarearduinobootloadersatmegad2>
   [/code]

   When the building ended, you should have “ATmegaBOOT_168_atmega328_pro_16MHzDiv2.hex” in the folder.

6. Use you ISP programmer, burn  “ATmegaBOOT_168_atmega328_pro_16MHzDiv2.hex” into ATmega328p chip. You do not need to reprogram the fuses but just in case you need, the fuse settings are:
   [code]
   HFUSE = DA
   LFUSE = FF
   EFUSE = 05
   [/code]

Now you can use your Arduino Nano just as an Arduino Pro Mini 3.3/8Mhz, write some blink LED program to test the new clock. Have fun with 3.3V devices!

The post Tutorial: 3.3V hacking for Arduino Nano appeared first on Digital Me.

Working as a software engineer for ten over years, I did not initially consider Adruino programming is of any difficulty. But I soon realized that I have been deeply spoiled by the modern operation systems. Giving a task that is so naturally to be implemented as a thread, it is never trivial in micro controller system. I spend one whole day to map out a flow chart of the control tasks, then turn the chart into C code. I can imaging that the time would have double or trippled if I don’t do this. Old school way rules, isn’t it?

I have attached the flow chart and Arduino sketch here. Sorry I dislike documentation, just refer to the inline comments and flow chart in case needed.

Having a license term is still better then nothing, so I make this one:

1. Tribute goes to Francisco Castro and his Luminch One project.
2. The redesign here is provided on AS-IS basis. If it works, it is designed by ba0sh1.
3. If it doesn’t work, I do not know who designed it

And enjoy the demo video. My first YouTube upload

The post Project Crystal (Part 2) appeared first on Digital Me.

The initial idea was stolen taken from Luminch One

I made several redesigns:

1. RGB LED strip instead of original high-powered LED
2. Use battery power.

The journey for battery power ends up to be much more complex. The major concern is standby (light off) power consumption. I wished the circuit could remain standby for at least one week. With three 3100mAh 18650 battery cell at 3.7V each, the maximum allowed current draw works out as 3100 * 0.8 / 7 (days) / 24 (hrs) = 14.7mA (reference here, number of cells actually does not help, but LED light needs 12V). However, the Arduino Nano alone consumes 20mA when running. After removing the power LED, it still consumes about 17mA. The distance sensor, Sharp GP2Y0A21YK0F takes another whopping 20mA. With these two monsters, standby time is 3100 * 0.8 / 37mA = 67 Hours ~ 2.8 days (show stopper).

It seems I need to turn off distance sensor and put Arduino into sleep mode during standby. It is solved by adding a Passive Infrared (PIR) sensor which powers on GP2Y0A21YK0F only when human (or pet) walks near the light. Together with AVR sleep mode the current now reduces to 2mA standby. My standby time is 51 days

Here comes the schematic.

Notes:

1. Q1 controls power to the Sharp sensor. I tried to drive this sensor directly from an Arduino pin but failed. The sensor output is unstable. I believe GP2Y0A21YK0F  specified 20mA power draw is only average value. Its peak current is quite higher.
2. Q2 is reverse voltage protection (reference)
3. J_LIGHT is the main RGB LED light. J_LIGHT_BK is for backup.
4. R1/R2 is voltage divider for battery voltage measurement.
5. J_INDI connects to a Bi-color (Red/Green) LED light as indication.

 The final construction will be on a perf-board. So I start Eagle PCB, set grid to 0.1inch and route the design. All files at the bottom.

Next part will include Arduino sketch, photos, and demo video. Stay tuned …

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