Dsc
02-04-2003, 02:26 AM
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I am looking for any help you could give me on DSC (direct servo control)
What I'm looking for is information as to how it works from TX to RX.
what kind of signal, power to the plug etc.
I'm working on a Robotics project, and have a bit of problem in this area.
Thank you for any help you can give me.
What I'm looking for is information as to how it works from TX to RX.
what kind of signal, power to the plug etc.
I'm working on a Robotics project, and have a bit of problem in this area.
Thank you for any help you can give me.
02-04-2003, 03:11 AM
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It works exactly the same as it normally does from the TX to the RX, it just doesn't RF modulate it. It's sends a raw serial stream down the DSC line (not sure what the pinouts are) The frame is a standard RC frame, which is a long frame pause, followed by each channels 1-2ms PPM location. The whole frame repeats every 20ms's so around 8 channels is max with a frame pause that's long enough to make sure it's not confused for data.
02-04-2003, 03:54 AM
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Originally posted by Lynx
It works exactly the same as it normally does from the TX to the RX, it just doesn't RF modulate it. It's sends a raw serial stream down the DSC line (not sure what the pinouts are) The frame is a standard RC frame, which is a long frame pause, followed by each channels 1-2ms PPM location. The whole frame repeats every 20ms's so around 8 channels is max with a frame pause that's long enough to make sure it's not confused for data.
It works exactly the same as it normally does from the TX to the RX, it just doesn't RF modulate it. It's sends a raw serial stream down the DSC line (not sure what the pinouts are) The frame is a standard RC frame, which is a long frame pause, followed by each channels 1-2ms PPM location. The whole frame repeats every 20ms's so around 8 channels is max with a frame pause that's long enough to make sure it's not confused for data.
02-04-2003, 04:12 AM
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If you plug a regular multi meter into a digital out pin you're going to get almost entirely random numbers. If you want to make sure, this is a bit of a hack but works well. And can actually provide ireful information. Make a simple L-PAD attenuator using a couple resistors. Like So
+Signal (input) ------R1----+-- +Signal (output)
|
R2
|
Ground (input)--+------------+-- Ground (output)
attenuation (in dB) = 20 * log10 ( (R1 + R2) / R2 )
Bellow are a couple good values to use
R1 = 10 kilohm AND R2 = 100 ohm ATTENUATION IS 40db
Wire the signal in to what you think the signal pin on the DSC cord is, wire the ground to the ground of the cable (you should be able to find that out at least) Wire the signal out and ground out to a standard phone jack, and plug that bad boy into your computer. Instant poor mans oscilloscope. The L-PAD for those of you that don't know, drops the signal down so you don't overload the sound card. Very very very few sound cards will conduct DC currents so you shouldn't have to worry about connecting to the power line, you just won't be able to hear anything. If you look around out there you can find a few freeware programs that will acts as simple scopes that will even help you edge trigger so you can see the length of at least a few of the signals in the frame.
Use this circuit at your own risk though folks.
+Signal (input) ------R1----+-- +Signal (output)
|
R2
|
Ground (input)--+------------+-- Ground (output)
attenuation (in dB) = 20 * log10 ( (R1 + R2) / R2 )
Bellow are a couple good values to use
R1 = 10 kilohm AND R2 = 100 ohm ATTENUATION IS 40db
Wire the signal in to what you think the signal pin on the DSC cord is, wire the ground to the ground of the cable (you should be able to find that out at least) Wire the signal out and ground out to a standard phone jack, and plug that bad boy into your computer. Instant poor mans oscilloscope. The L-PAD for those of you that don't know, drops the signal down so you don't overload the sound card. Very very very few sound cards will conduct DC currents so you shouldn't have to worry about connecting to the power line, you just won't be able to hear anything. If you look around out there you can find a few freeware programs that will acts as simple scopes that will even help you edge trigger so you can see the length of at least a few of the signals in the frame.
Use this circuit at your own risk though folks.
02-04-2003, 01:47 PM
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Originally posted by Lynx
If you plug a regular multi meter into a digital out pin you're going to get almost entirely random numbers. If you want to make sure, this is a bit of a hack but works well. And can actually provide ireful information. Make a simple L-PAD attenuator using a couple resistors. Like So
+Signal (input) ------R1----+-- +Signal (output)
|
R2
|
Ground (input)--+------------+-- Ground (output)
attenuation (in dB) = 20 * log10 ( (R1 + R2) / R2 )
Bellow are a couple good values to use
R1 = 10 kilohm AND R2 = 100 ohm ATTENUATION IS 40db
Wire the signal in to what you think the signal pin on the DSC cord is, wire the ground to the ground of the cable (you should be able to find that out at least) Wire the signal out and ground out to a standard phone jack, and plug that bad boy into your computer. Instant poor mans oscilloscope. The L-PAD for those of you that don't know, drops the signal down so you don't overload the sound card. Very very very few sound cards will conduct DC currents so you shouldn't have to worry about connecting to the power line, you just won't be able to hear anything. If you look around out there you can find a few freeware programs that will acts as simple scopes that will even help you edge trigger so you can see the length of at least a few of the signals in the frame.
Use this circuit at your own risk though folks.
If you plug a regular multi meter into a digital out pin you're going to get almost entirely random numbers. If you want to make sure, this is a bit of a hack but works well. And can actually provide ireful information. Make a simple L-PAD attenuator using a couple resistors. Like So
+Signal (input) ------R1----+-- +Signal (output)
|
R2
|
Ground (input)--+------------+-- Ground (output)
attenuation (in dB) = 20 * log10 ( (R1 + R2) / R2 )
Bellow are a couple good values to use
R1 = 10 kilohm AND R2 = 100 ohm ATTENUATION IS 40db
Wire the signal in to what you think the signal pin on the DSC cord is, wire the ground to the ground of the cable (you should be able to find that out at least) Wire the signal out and ground out to a standard phone jack, and plug that bad boy into your computer. Instant poor mans oscilloscope. The L-PAD for those of you that don't know, drops the signal down so you don't overload the sound card. Very very very few sound cards will conduct DC currents so you shouldn't have to worry about connecting to the power line, you just won't be able to hear anything. If you look around out there you can find a few freeware programs that will acts as simple scopes that will even help you edge trigger so you can see the length of at least a few of the signals in the frame.
Use this circuit at your own risk though folks.
Since I am able to operate the receiver from the Tx via DSC cable provided, I do have the pin out, but from the TX I don't get the voltage at the Red wire pin nor at the black wire pin which these are/should be comon to the wires at the receiver end should it not?
My problem at this point is I need to have the power at the TX level to power my Fiber Optic encoder.
02-04-2003, 07:47 PM
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Hi,
The principle of DSC is quite simple
The receiver must be fitted with a DSC-connection (or you'll have to find it by yourself)
The receiver the need following :
Ground
+5 volt
PPM (or PCM)- signal (depending on what receiver is used)
(the lay-out of the original Futaba DSC-cable is to be found here :
http://users.belgacom.net/TX2TX/tx2t...h/tx2txgb7.htm )
The signal is fed on the receiver between the HF-decoder and the encoder which is encoding the signal to a useable signal for the servos.
Some transmitters do not have a +5V connection at their buddy box connection. Simply find that power source somewhere inside the transmitter.
For PPM-signal characteristics and links, see my website chapter 1. Same for a downloadable simple free scope with which you can find a PPM-signal.
Olivier
The principle of DSC is quite simple
The receiver must be fitted with a DSC-connection (or you'll have to find it by yourself)
The receiver the need following :
Ground
+5 volt
PPM (or PCM)- signal (depending on what receiver is used)
(the lay-out of the original Futaba DSC-cable is to be found here :
http://users.belgacom.net/TX2TX/tx2t...h/tx2txgb7.htm )
The signal is fed on the receiver between the HF-decoder and the encoder which is encoding the signal to a useable signal for the servos.
Some transmitters do not have a +5V connection at their buddy box connection. Simply find that power source somewhere inside the transmitter.
For PPM-signal characteristics and links, see my website chapter 1. Same for a downloadable simple free scope with which you can find a PPM-signal.
Olivier
02-04-2003, 08:48 PM
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I don't think it's reasonable to expect the transmitter to supply the 5 V to the receiver. Depending on the servos installed, over 5 A could be required. That's a lot of dissipation for a regulator fed from a 9.6 V transmitter battery, or even a 7.2 V battery (as used by Multiplex, I think).
Just use a normal receiver battery arrangment, as if the robot was under radio control. The receiver will be powered by the same battery, whether under radio or DSC control.
As far as the transmitter is concerned there is no difference between driving a DSC cable and being the student end of a buddy cord. The DSC plug should have a link to power up the encoder portion of the transmitter. A make-contact on the jack which closes when the plug is inserted can be used instead.
The Futaba 9Z can measure the level of the receiver supply. The receiver voltage is fed back up the + lead of the DSC cable. This is reason for a 3-wire cable. The ground lead is used as a reference for the DSC signal as well as the voltage signal. I don't know whether Multiplex do it this.
Just use a normal receiver battery arrangment, as if the robot was under radio control. The receiver will be powered by the same battery, whether under radio or DSC control.
As far as the transmitter is concerned there is no difference between driving a DSC cable and being the student end of a buddy cord. The DSC plug should have a link to power up the encoder portion of the transmitter. A make-contact on the jack which closes when the plug is inserted can be used instead.
The Futaba 9Z can measure the level of the receiver supply. The receiver voltage is fed back up the + lead of the DSC cable. This is reason for a 3-wire cable. The ground lead is used as a reference for the DSC signal as well as the voltage signal. I don't know whether Multiplex do it this.
02-04-2003, 11:21 PM
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Thanks guys for the information.
Olivier, on your web site, you show some Multiplex, but I don't see the Multiplex DSC, do you know what it is?
Olivier, on your web site, you show some Multiplex, but I don't see the Multiplex DSC, do you know what it is?
02-10-2003, 08:11 PM
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Hi Roger,
I asked a French and German newsgroup, and I received an answer from the Frenchies : "Yes, a DSC-cable is sold since long ago by and for Multiplex radios, long before Futaba had such a system."
That's all I have, no other details.
Good Luck,
Olivier
I asked a French and German newsgroup, and I received an answer from the Frenchies : "Yes, a DSC-cable is sold since long ago by and for Multiplex radios, long before Futaba had such a system."
That's all I have, no other details.
Good Luck,
Olivier
02-10-2003, 08:25 PM
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Originally posted by olivier
Hi Roger,
I asked a French and German newsgroup, and I received an answer from the Frenchies : "Yes, a DSC-cable is sold since long ago by and for Multiplex radios, long before Futaba had such a system."
That's all I have, no other details.
Good Luck,
Olivier
Hi Roger,
I asked a French and German newsgroup, and I received an answer from the Frenchies : "Yes, a DSC-cable is sold since long ago by and for Multiplex radios, long before Futaba had such a system."
That's all I have, no other details.
Good Luck,
Olivier
02-11-2003, 01:10 PM
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Hi Roger, again me,
I received some details about DSC on Multiplex : I was told that the place for the battery plug on a Multiplex receiver consists of following connections :
1) the ground V- (of course)
2) the positive voltage V+ (of course)
3) the PPM-in (or as you want it : the DSC-connection)
With an original (non-uni-plug) Multiplex switch, it is posible to connect the DSC-cable to that switch (normally for charging receiver-battery) and to control the receiver.
Succes,
Olivier
I received some details about DSC on Multiplex : I was told that the place for the battery plug on a Multiplex receiver consists of following connections :
1) the ground V- (of course)
2) the positive voltage V+ (of course)
3) the PPM-in (or as you want it : the DSC-connection)
With an original (non-uni-plug) Multiplex switch, it is posible to connect the DSC-cable to that switch (normally for charging receiver-battery) and to control the receiver.
Succes,
Olivier
02-11-2003, 01:16 PM
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Originally posted by olivier
Hi Roger, again me,
I received some details about DSC on Multiplex : I was told that the place for the battery plug on a Multiplex receiver consists of following connections :
1) the ground V- (of course)
2) the positive voltage V+ (of course)
3) the PPM-in (or as you want it : the DSC-connection)
With an original (non-uni-plug) Multiplex switch, it is posible to connect the DSC-cable to that switch (normally for charging receiver-battery) and to control the receiver.
Succes,
Olivier
Hi Roger, again me,
I received some details about DSC on Multiplex : I was told that the place for the battery plug on a Multiplex receiver consists of following connections :
1) the ground V- (of course)
2) the positive voltage V+ (of course)
3) the PPM-in (or as you want it : the DSC-connection)
With an original (non-uni-plug) Multiplex switch, it is posible to connect the DSC-cable to that switch (normally for charging receiver-battery) and to control the receiver.
Succes,
Olivier
Again, thanks for any assistance.
Roger
02-11-2003, 09:54 PM
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I just did a search for 9C DSC and it came right up.
http://www2.towerhobbies.com/cgi-bin...sc&FVPROFIL=++
http://www2.towerhobbies.com/cgi-bin...sc&FVPROFIL=++
