The LCDuino-1 I/O processor

[linuxworks]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif cat5?

too bulky. even rj11 (4 pin is all you need) is too large. this is board-to-board not chassis-to-chassis.

for the chassis case, THAT would be a good use! but I want a small connector that can take me from a board that is the size of a small lcd to another small board in the chassis (might be a relay board or PGA board or even 'managed power supply' board with controller logic there.

 

[m1abrams]

87833-0441 Molex Headers

whole page of em
http://www.mouser.com/Interconnects/...z0wxnw&FS=True

 

[linuxworks]

maybe something like this:

Digi-Key - WM1796-ND (Manufacturer - 43045-0414)

 

[m1abrams]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif maybe something like this: Digi-Key - WM1796-ND (Manufacturer - 43045-0414)

I like it. I also am partial to right angle versions too for low profile.

 

[glt]

JST 2.54mm 3-pin through hole connector pack

 

[luvdunhill]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif too bulky. even rj11 (4 pin is all you need) is too large. this is board-to-board not chassis-to-chassis. for the chassis case, THAT would be a good use! but I want a small connector that can take me from a board that is the size of a small lcd to another small board in the chassis (might be a relay board or PGA board or even 'managed power supply' board with controller logic there.

ah, I was assuming this was an external connector. For internal, I like the connectors that FCI makes. Check Digikey, Newark, Mouser etc. About as low profile as you can get.

 

[linuxworks]

Quote:

Originally Posted by glt /img/forum/go_quote.gif JST 2.54mm 3-pin through hole connector pack

need 4 pins, not 3. they got any ones with 4?

 

[glt]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif need 4 pins, not 3. they got any ones with 4?

I Don't know. That is a good shop though and very responsive with email.

 

[linuxworks]

new feature for today - lm75a support

just some hand soldering directly to the chip with ribbon cable

connect in to i2c pins (28 and 27 on the ard chip), run some code such as:


Wire.beginTransmission(my_dev_addr);
Wire.send(0x00); // 0 = 'temperature register'
Wire.endTransmission();

Wire.requestFrom((uint8_t)my_dev_addr, (uint8_t)2); // read 2 bytes
while (Wire.available() < 2) { } // note the null loop!

val = (Wire.receive() << 8); // MSB
val |= Wire.receive(); // LSB

// now, deal with the funky lm75a bit-shifting
shifted = (val >> 5);
val_f = (float)shifted * 0.125;

return val_f;


and that's it. you get direct digital-reading degrees in C.

with 3 bits of addressing for this chip series, you can have 8 of these on the common i2c bus and poll them all you want.

one per heatsink? perhaps! lol

...anyway, one more 'driver' ready for the volumaster code base.

 

[srserl]

I would like dc offset protection for my preamp...is the arduino fast enough at detecting and switching output? If not, would it be possible to have it work with an epsilon-12-like circuit and allow the arduino to override the e-12 if there is no dc (and switch off the output), but not allow it to override (and switch on the output) if the e-12 has switched off output due to dc offset?

 

[amb]

While arduino is "fast enough", you won't save any circuitry by involving it for DC offset sensing. You'll still need the LPF, and since DC offset could be either polarity, you'd either need to use an "absolute value" circuit to feed an arduino's a/d input, or use the existing ε12-style output to toggle a digital input on the arduino...

 

[srserl]

Hmmmm,
Using the ε12 output to trigger the arduino might be a good way...just set an interrupt on the state change of the pin and use that to trigger a dc offset state. Then, just make sure that the dc offset state is always used when setting the state of the relay.
The only reason for me to do it this way is to avoid an extra relay in the signal path as there will be enough relays as it is.


Wi

 

[amb]

Yep. Since we are planning a relay-based output selector app, it'd be a simple matter to make it disconnect all outputs based on an external trigger. I'm not even sure the arduino would need to be involved in this at all, just some logic on that board. OTOH, it might be cute to have the LCD display this condition...

 

[linuxworks]

my take on it is that there is room (in my vision) for a 'management module' that also includes environmental monitoring (like the big boy routers and switches do). it could check for dc offset, bias (where it makes sense), voltage rail levels and temperature of key points. if any of those 'look' like trouble could be happening, a fast disconnect (power off and relay tripping to disconnect spkrs/phones) would be in order.

I could see the cpu making some decisions that would be way beyond simple analog electronics to be able to do.

its not in my near-term plans but it is part of The Vision(tm)

 

[amb]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif ... its not in my near-term plans but it is part of The Vision(tm)

While I think that's all very cool, and coming from a background of fault-tolerant computers where even seconds of system downtime could mean millions of dollars lost, I lived and breathed that stuff, I could certainly understand the attraction. But the audio purist in me also says that some of this goes far beyond what's necessary, and gets into the realm of complexity for complexity's sake. Afterall, a stereo is not a mission-critical computing platform, oftentimes the simpler solutions are the most reliable.

The LCDuino-1, in my mind, allows us to get around the limitations of antiquated items like volume pots, cleaning up signal wiring, and while we're at it, provide the convenience of remote control and simplified front panel. But it is also an opportunity for wretched excess... Just because there is a CPU doesn't mean that it has to be in the middle of everything.

I am not opposed to the concept of CPU control where it makes sense, but as we go down this path of possibilities, we should not forget the K.I.S.S. principle.