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1  Using Arduino / Audio / Re: Arduino library for WTV020-SD-16P audio module on: February 16, 2013, 02:42:50 pm
For easy testing , load the microSD with sample .AD4 files provided in other links. Make sure to format the uSD to 16bit .  Power WTV020 pin 16 & 8.   I would just touch pin 9 or pin 13 to ground for playing the file. Touch pin 1 to reset the chip. The audio output is very low power. I used a speaker from a cell phone to pins 4 & 5 and held it really close to my ear to hear it. Once you get some confidence the sound files are working, you can add a LM386 amplifier, or I bought a 12V 15W amp module on ebay for $6.  After that can build on more controls functions. I also found the WTV020 cant really do MP3 mode unless you specifically buy it that way. Strangely I can force the WTV020 to operate like MP3 mode by interfacing with TTL gates or dry relay contact for a trigger. Using optocouplers or soliud state relays just didnt cut the cheese.,115411.0.html  more info here
2  Using Arduino / Motors, Mechanics, and Power / Re: Arduino internal power supply driving capabilities on: December 28, 2012, 11:30:01 pm
Have an original homebrew project using the WTV020-SD-16P. The WTV020 3.3V power is provided from an Arduino UNO.  A PIR motion sensor is wired to a TTL NAND gate chip, and interlocked with the WTV020 pin 15 "BUSY" signal.  If the PIR senses movement and the WTV020 is not running, a TTL NAND gate output   wired to WTV020 pin 13 goes to zero, triggering the WTV020 to play the next sound file.  The BUSY signal is also wired to an Arduino input to count & sequence LEDS & animation action.    .

A second prototype of this project is in process, using an Arduino 2560Mega instead of the UNO.  Eliminated the TTL HW, direct wire IO to control the WTV020. Have tried 2 different WTV020 modules, both cause the Mega to overheat the 3.3V power supply chip.  A cheap Buck switching power supply is then used to provide 3.3V (from a 5V bulk supply).  The Arduino is fed 12V from a separate supply, COM grounded ( ground prong of 115VAC plug). There is a 5v 5a bulk supply also with COM tied to ground. All COMs are ohm checked to ground.  There was a buzz getting thru the 15W audio amp, adding a series ferrite core choke from the 3.3V supply to the WTV020 squashed the noise. ( Later I also added a 100 mike cap across the 3.3 V supply, and 6 ohm load to ensure continuous current on the 3.3V supply )

Now, the problem: Both WTV020s have somewhat misbehaved. The first WTV020 would lock up if the NEXT pin was grounded while it played. A reset by cycling power or grounding pin 1 would allow it to restart. Still used it to continue working on the project until a replacement arrived.  Once the WTV020 was triggered by grounding pin13, it would not stop at the end of the sound file, it would continue onto the next sound file.

A replacement WTV020 arrived, seemed OK when first tested. Now it does the same thing, once triggered after powerup, it keeps running. Tried using optocouplers ( a 4N35 OMRON 61B1 solid state relay) and then a relay contact to trigger the WTV020, no change. All the WTV020 input pins read the same Vcc 3.3V open circuit. usually when I grounded the pin 13 to trigger , a 1k resistor was in series just in case.
Wondering if I just have bad luck, or if I am missing something in troubleshooting ( been testing things for 2 weeks ). Now waiting for the next WTV020 ordered ( 3rd one) to get here.  The first protoype has a 5V supply from TTL triggering the WTV020 with no trouble. This protoype has no TTL interface, wondering what else could be different between UNO and MEGA, the interface is minimal anyway.......any ideas or experiences ?   
3  Using Arduino / Motors, Mechanics, and Power / Re: Arduino internal power supply driving capabilities on: September 16, 2012, 09:09:37 pm
I've powered a WTV020-SD-16P  from the Arduino 3.3 V power supply. Is there any concerm driving serial lines or the discrete control inputs of the WTV020 from the 5V Arduino ?  Is there a suggested series resistance , voltage divider , or optical isolation from Arduino outputs to the WTV020 inputs ?

I tried moving the solder jumper on the WTV020 to 5V from 3.3 V , and it didnt work, so I had to put it back.
4  Using Arduino / Project Guidance / Re: WTV020-SD-mini on: September 16, 2012, 09:02:57 pm
I fixed my problem by loading .ad4 files to the SD card. The .mp3s needed first convertered to mono and 6kHz .wav files, then to .ad4s.  Sounds sweet
5  Using Arduino / Motors, Mechanics, and Power / Re: Arduino internal power supply driving capabilities on: August 21, 2012, 07:40:44 pm
Thank you Michael & Left for the great advice.

To summarize, the servo control input is a high impedance {  >5k ? } so the arduino pin load is well under the Arduino pin's max rating.

The servo power needed is highly variable, even with small micro servos. The plastic gears may be stickier, stiffer & spongy than the metal ones, acceleration and sudden direction change highly impacts the needed torque current to where it could easily exceed an UNO's available 5V power of 200 mA even with one servo.

I had wired a12V 3A power supply and a 5V 4A power supply for my project. After thought and advice, will use the 12 V to power the arduino & audio amps, the 5V supply will be used for servos and LEDs.

Thanks for the shield recommendations, too.


6  Using Arduino / Project Guidance / Re: 5x5x5 Led Cude Powering Question on: August 21, 2012, 07:21:40 pm
Very cool project, and great advice from Lefty.
Just wanted to add some LED basics. 
1) The LED will be defined by its output brightness in millicandles. Its tough to quantify except to compare LEDS to each other , the more mcds, the brighter it can be.
2) The LED will have a rating called Vf. This is the forward voltage, how much volts it takes when turned on ( positive voltage applied to the anode + side ).
If the LED has a Vf of 3 volts, & If the arduino drives it with 5 volts, there are 2 volts leftover that have to be used by a resistor ( if a device regulates the LED current, the resistor isnt needed.) it takes knowing #2 & #3 to pick a resistance.
3) The LED has a rating called If - this is the continuous forward current. If the LED is driven to ON, and stays on for several seconds or more, you want to keep the LED under this rating to not eventually burn it out.  to pick this resistor if there are 2 volts leftover for the resistor to use, divide by the If ( in mA) to pick the resistor in kilo-ohms.  For example, if If = 20 mA, 2 V / 20 mA = .1 kohms ( that is 100 ohms ) for prototyping arduino projects, I generally just use a 220 ohm resistor for indication.
4) If the LED is used in a for short times like in a scanned or pulsed circuit, there is a maximum value for current called Peak Forward Current ( for example 1/10th duty cycle, 0.1ms pulse width) where the resistor can be sized using the peak current value that is much higher, for example 70 mA ( 3 1/2 times the continuous rating ) and the resistor value can be much smaller to allow this peak current.

7  Using Arduino / Motors, Mechanics, and Power / Arduino internal power supply driving capabilities on: August 20, 2012, 06:27:31 pm
My animatronics project will use 3 or 4 servos, several SSRs for LED drivers & other peripherals.

It looks like the Uno can drive 5V @ 40ma per pin, but not to exceed 200mA total for all pins.
The 9g TowerPro SG90 microservos do not specify rated current VS speed / torque . I have 2 servos running direct drive eyeballs from an UNO as a test, so far havent failed anything.  Is there a rule of thumb available about driving servos loads ? Does it make sense to supply servo power separately and just use the PWM output ? ( making sure both supplies reference the same common )

The 3.3 V power supply specs 50mA available, hopefully enough to power a WTV020-16P audio player.

The Mega2560 has alot more IO , still has 40mA per pin limit, and the 5V voltage regulator chip NCP1117ST50T3G is spec'd at 1A max , but with a caveat that it can do 1500mA but may thermally protect itself.

Can the Mega2560 circuit board traces and connectors handle 1 A steady state ?
8  Using Arduino / Audio / Re: WTV020-SD-16P - Help & solution tree on: July 23, 2012, 08:08:39 pm
Thank you, the link takes to good solution areas. Having alot of good luck using the AD4 converter, IMHO, it is key to have successful sound tracks copied to the uSD card.
9  Using Arduino / Audio / WTV020-SD-16P - Help & solution tree on: July 22, 2012, 12:27:42 pm
I spent a several days ( 12-15 hrs ++)  trying to get a WTV020-SD-16P to work as a standalone sound player, just as a test for my project. 
It did finally work as a standalone. If I can do it, so can you, from this test setup, the experience can be built on.
I used a buck power supply ( cost less than $2 ) to get the 3.3 V from a 5v power supply ( the 5V power supply is a cell phone charger ). 

Some really good information is scattered in the forum, so I started a post here just for listing best practices and troubleshooting tips.

My big problem: Wired very simply as shown, MP3 mode, when the play was triggered by connecting pin 9 to ground, all that came out was a feeble 1/2 sec beep. It didnt matter if the SD card was blank or had files on it. 
Root problem was the micro-SD memory card. It worked fine connected to my PC thru a card reader.
The needed advice, not found in vendor documentation, is: " Before the memory card can be used it must first be formatted with FAT16 option."

After reformatting the memory card, copied sample .ad4 files to the card & voila ! success !
I'd thought the files would be limited to 20 seconds, these sample ad4s seem to be alot longer than that.

I also wired pin 2 [DAC +] up to a 15W amp to drive a car speaker. There is a loud POP when the sound files starts and stops, not sure of a DC blocking capacitor will fix that.   Any suggestions ?

P.S. the LED goes out when pin 15 "BUSY" output goes high, so the LED really should be labeled "Not Busy".
After the aggravation of getting started is over, this inexpensive module looks to have alot of capability and uses for many fun hobby projects.
10  Using Arduino / Project Guidance / Re: What were they thinking? on: July 21, 2012, 11:08:46 pm
to make it worth the while to spend $3 on a shield fab.
11  Using Arduino / Project Guidance / Re: WTV020-SD-mini on: July 21, 2012, 11:07:47 pm
Its got me baffled too.

Hardwired as MP3 mode When I trigger pin 9 , all I get is a beep. I tried several wav files, and even reconfigured those wav files to ensure they had the proper bit rate. I tried the sample ad4 files found in this forum, and then tried mp3s.  I'm using a 1Gb scandisk SD card.

Simply 3.3V into VDD pin 16, an LED with 500 ohm resistor to pin 15, pin 8 wired to COM. Tie pin 9 to ground to trigger. Get nothing but a short beep. The LED does go out while it beeps. I'm using a cell phone speaker - the chip doesnt drive a 1/4 W speaker.
The chip doesnt play files at all from memory.

Wonder what I'm doing wrong ................not sure what to ask the vendor.
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