Member Since: December 15, 2008

Country: United States

  • Has anyone had any luck hooking this up to an STA540? I had no problem with my amplifier hooking directly to speakers, but once I hooked it up to the RN52 bad things ensued. First when I went to 12V to power the amplifier I was getting loud pops and I can see the PSU flickering on and off in cadence with the pops. I turned the power down to 9V and the pops became less, though still there, and the flickering stopped. My volume was lower, obviously, and I was still getting a lot of hiss when nothing was playing. I’m thinking I’m dealing with a ground loop. I am using two separate power supplies. I have tried sharing a ground between the two, but that just made the problem worse (which, again, supports the ground loop theory). I did notice that there is a separate audio ground on the chip - AGND - but that pin is not brought out to the breakout board. Is it wired to digital ground on the board? Would I need AGND to be referencing my audio ground?

  • Can you control the backlighting by using PWM on the backlight voltage pin? It’s connected to Vss by default which applies the entire 5v to the pin, but if I can PWM the pin and apply a lower voltage will that dim the display? In essence I’m looking for a way to dim the display using an MCU. Also, when dimmed does it draw less current? (I’m thinking it does, less photons means less work which means less current).

    Also, I’m assuming that a lot of current is most likely drawn from that backlight pin so I plan on placing a transistor between the MCU and the LCD which I will drive from the MCU via PWM.


  • Could I use this for Audio? I want to drive it from my Due using some DDS routines I’ve worked out. (yes, I know the Due has DAC pins, but they are sensitive and I don’t want to risk blowing them out, hence an external board). I plan on sampling at 48khz so I’m fairly certain there aren’t any bandwidth issues on the I2C bus. I’m just concerned about response and whether it will work for a simple audio solution (not audiophile status at all).

  • Quick question regarding the DUE and the DAC. I want to hook up the DAC output of my DUE to an STA540 (I bought the kit), but I was concerned since the DAC outputs for the DUE seem especially sensitive from what I’m reading around the web. I’m pretty sure the opamp at the input of the kit has a fairly high input impedance so I doubt it draws a lot of current, but I want to make sure before I hookup my $50 due to the amplifier and blow my DAC output. I’ve tried unsuccessfully for three nights in a row to get something to play through an lm386 circuit, but no joy. I know the DAC is working though because I see a nice 440hz 1.2vpp sine wave on my scope when I probe the DAC (I’ve got a DDS running on the DAC which is generating A4 which is 440hz).

  • Quick question - how does this board compare to the new Arduino Zero?

  • Google Chrome´╗┐ because they are the most mature with the new W3C audio and video specs. I wrote a mini-moog emulator and a step sequencer - both in pure javascript and HTML5 (no flash). It runs well in Chrome, not so well in Mozilla Firefox´╗┐, and not at all in IE.

  • Most beginner 2 channel fixed wing craft come with rudder and elevator control. Aileron control is considered an advanced control option and you MUST have elevator or you will end up stalling a wing (I saw that happen a couple of times, not sure if it was due to the limited chord angle or something else). If I were going for basic control, rudder and elevator are a good combination. With the combination of pitch and yaw you can get some decent bank angles - everything will be uncoordinated so you will be crabbing all over the place, but at least you have pitch control. Also, with pitch control you can always trade altitude for airspeed easily - which you sometimes need to prevent a stall.

  • Here’s an anecdote for you (hopefully I don’t get anyone in trouble over this). I ordered the Audio Amplifier Kit - STA540 about a year ago. During the soldering process I accidentally lifted a pad. I asked about a bare PCB so I can continue (I made the mistake early on). While Sparkfun does not offer bare PCB’s for that kit, Mike sent me out a completely new replacement! I still owe him a video of my MAME machine working with the STA540 :). You would NEVER get that kind of customer support from digikey / mouser. I’m just another number to them - a small number at that. Sparkfun treats you the same whether you have ordered $20 or $2000 worth of parts. For my DIY fix, Sparkfun is the go to place for me.

  • I just read the entire article - doh - and I noticed the link to the github repo. Check it out. Once I cloned the repo everything built and ran fine.

  • “Although nice, these tutorials are really kind of designed for someone who has knowledge and background in logic design and FPGA development.”

    This statement doesn’t make sense to me. You SHOULD have some knowledge and background in logic design before attempting to program FPGA’s. In fact, at the bottom of the wikipedia link you placed there is a section that describes the prerequisites. On there are Boolean operators AND, OR, NOT, and XOR. They also suggest a familiarity with low level languages like C or C++. I concur with those prerequisites.

No public wish lists :(