Detecting Standby mode?
Posted by: ewodzien
Detecting Standby mode? - 02/12/2004 20:57
Hi:
In my quest for wirelessly connecting my Empeg to my PC, I have sourced all the parts and have one remaining question that seems to elude me:
How can I detect when the Empeg is in standby mode so that I can power a wireless bridge?
Any type of signal is fine, I was hoping I could use a RTS/CTS?CD pin on the serial port, but I found out that the port doesn't have those pins. I can't use the amp off/on wire because it is off when the unit is in standby.
I think I have to open the unit and tap off of a pin somewhere, but would like to avoid that if possible.
Once I figure this out (hopefully with help from this board), I'll have a wireless connection that doesn't drain my battery and doesn't require user intervention so that my daily radio shows automatically get downloaded to my empeg.
Many many thanks!
-Ed
Posted by: tfabris
Re: Detecting Standby mode? - 02/12/2004 21:15
Amp remote line goes high when the VFD display is on, goes low when the VFD display is off.
Telling the difference between full-power-off and Standby is a different animal. Not sure if you need that or not?
Edit: reading your post more closely you say you can't use the amp remote line. So I assume that what you're asking for is a way to tell the difference between full-off and stanby. Sorry.
Posted by: wfaulk
Re: Detecting Standby mode? - 02/12/2004 21:24
I don't think I'm following. There are three possible states: off, standby, and on. You want a signal in which states? I'd have guessed on and standby, thus your dilemma, but your subject line seems to be pointing in the wrong direction for that.
Assuming I'm right anyway, isn't there something you could put in the way of the power cable to detect when juice is flowing? Seems like a relay put in series with that line switching something else would work. But I could be wrong.
Posted by: ewodzien
Re: Detecting Standby mode? - 02/12/2004 21:49
Thanks for the quick answers so far-
Clarification:
I would like a signal (any kind- +5V/GND/+12V), anything when the unit is in standby mode. So that while the car is parked in the garage of my home, it will receive updates.
The standby signal will power a relay which will switch power for the wireless bridge connected to the ethernet port.
Since I have my standby time at 30 mins, after 30 mins the empeg and the wireless bridge will shut off and my battery will be saved.
If there is no known way of detecting standby externally, does anyone know of a pin/pad internally I could tap?
-Ed
Posted by: tfabris
Re: Detecting Standby mode? - 02/12/2004 21:59
What Bitt and I are trying to say is that the player has more than just two possible states. You need to think this through carefully.
You are asking for a way to tell the difference between "In standby" and "not in standby".
But the thing is, the player doesn't just have those two states. It has three states:
-Off
-Standby
-On
You need to know whether your goal is to detect all of these states, or if you only need to detect two states, and if so, then which two you want to detect between?
Posted by: wfaulk
Re: Detecting Standby mode? - 02/12/2004 22:12
And it seems to me that you ought to be able to detect any of those states by checking the power and amp lines.
Off/Off = Off
On/Off = Standby
On/On = On
I don't think it'd be able to get into Off/On state. Not without magic or a short, anyway.
Posted by: ewodzien
Re: Detecting Standby mode? - 03/12/2004 05:39
Yes, I know there are three states. But I only care about two. In standby or not in standby.
Actually, the following logic table(s) would work:
State - Output to power wireless bridge.
Off - Off
On - On
Standby - On
Even the table below would work:
State - Output to power wireless bridge.
Off - Off
On - Off
Standby - On
Again, I just want the wireless bridge power supply to shut off when the empeg shuts off to save the battery.
wfaulk: What do you mean by power line? The ignition? If so, ignition line is off when unit is in standby.
I don't see how looking at the amp line and the power (memory?) line would do what I want.
I hope this clears things up.
-Ed
Posted by: Roger
Re: Detecting Standby mode? - 03/12/2004 06:07
Quote:
Yes, I know there are three states. But I only care about two. In standby or not in standby.
This is what Tony and Bitt have been trying to explain. "Not in standby" is not a single state. It's two: Off and Fully-On.
You see, we're all pedants around here...
Quote:
I hope this clears things up.
It does. Now we know which two of the three states you want the wireless bridge powered in.
Posted by: mdavey
Re: Detecting Standby mode? - 03/12/2004 08:12
I think I finally understand what ewodzien is asking. There is actually another state: Empeg present in sled.
ewodzien wants an accessory powered up when the Empeg is present and in standby mode; and powered down when the Empeg isn't present or has no power.
The accessory will be connected to the Empeg via the sled (so the accessory will still be connected to the sled wiring when the Empeg is removed).
The problem is that the only power output provided by the Empeg (the Ant remote), is switched off when the Empeg is in standby.
You could build a circuit to test for the difference between connection to ground and high impedence on the Ant line. This effectively has three states:
~12v dc - Empeg in "On" mode
0v - Empeg in "Standby" mode or unpowered
High Impedence - Empeg not in sled.
If the circuit were powered from the power line (on the sled, this is the yellow wire that goes through the inline fuse) rather than its own power source, the logic out of your high impedence detector would look like this:
Low - Empeg in "On" or "Standby" mode (or unpowered)
High - Empeg not in sled.
So if you want the accessory powered in "On" and "Standby" modes, you just invert the output:
High - Empeg in "On" or "Standby" mode
Low - Empeg not in sled (or unpowered)
If you want the accessory powered in "Standby" mode only, invert the output then AND it with the inverted Ant. power output.
[edited: corrected detector logic]
Posted by: mdavey
Re: Detecting Standby mode? - 03/12/2004 09:07
Quote:
If you want the accessory powered in "Standby" mode only, invert the output then AND it with the inverted Ant. power output.
In this particular case, the high-impedence detector can be replaced with a couple of transistors (so other accessories don't see a high when they expect a low) and a pull-up resistor (high side connected to the power line). The second transistor can act as an inverter too, so the result is logical high in standby and logical low when the sled is unpowered, the Empeg is removed from the sled or the Empeg is on.
Posted by: genixia
Re: Detecting Standby mode? - 04/12/2004 00:57
It'd probably be easier to invert the switched 12V line (1 transistor, 2 resistors) and feed that to a 555 timer set up as a monostable multivibrator with R=10M and C=330uF. Output will probably need a driver stage to drive the relay - another transistor, a diode, a couple more resistors.
Posted by: canuckInOR
Re: Detecting Standby mode? - 04/12/2004 04:53
Quote:
There are three possible states: off, standby, and on.
Quote:
In standby or not in standby.
Quote:
I think I finally understand what ewodzien is asking. There is actually another state: Empeg present in sled.
Then, shalt the states be numbered three, no more, no less. Three shalt be the number of states, and the number of states shalt be three. Four shalt thou not count, nor either count thou two, excepting that thou then proceed to three. Five is right out. Once the number three, being the third number, be reached, then thou shalt have reached the full number of states.
My most sincere apologies.
Posted by: Chuck
Re: Detecting Standby mode? - 04/12/2004 05:00
Thank you so much for that.
Posted by: mlord
Re: Detecting Standby mode? - 17/12/2004 04:08
How about one of the serial port lines.. there must be something there that registers +12V/-12V when the empeg is not OFF, and 0V when it is OFF (?).
If so, then software could be modified to control the state of said signal to help the external hardware (relay) distinguish between standby and "on".
Posted by: genixia
Re: Detecting Standby mode? - 17/12/2004 04:21
Hmm, you could probably connect a monostable multivibrator to the TxD line of the sled, and change the RC time to be in the order of a couple of minutes. Enable notify=1 and the data should be enough to retrigger it. Then the kernel would just need to be changed to pump out the occasional data bit during standby (a byte every minute would do it). I'd suggest masking this standby byte with "Apps use serial port" to prevent data being sent to eg GPS devices.
Posted by: Ezekiel
Re: Detecting Standby mode? - 17/12/2004 13:30
Quote:
monostable multivibrator to the TxD line
I have no idea what this means, but it sure sounds like a body could have a lot of fun with one. 
-Zeke