Billyk
500+ Head-Fier
- Joined
- Oct 18, 2005
- Posts
- 567
- Likes
- 10
Yeah, that's the beauty part about this project! Plug and play if you want or you can play with programming...add different bits, whatever! The sky's the limit.
The LCDuino-1 I/O processor
- Thread starter amb
- Start date
jtostenr
Head-Fier
- Joined
- Mar 28, 2009
- Posts
- 70
- Likes
- 0
I'm sure this was mentioned somewhere before, but I can't seem to find it. What is the depth of the LCDuino? How much space behind the front panel does it require?
Jeff
Jeff
Quote:
With the connectors I have used for attaching the momentary switch, and the connector for the programming cable, mine is about 1.25 inches from the front of the pcb to where the wires come out of the connectors on the back. The lcd sticks out about 5/16ths inch from the pcb.
How you choose to mount it, and how much space you need behind it will depend on the thickness of your front panel, and how you shim or hollow out the front panel to have the front of the lcd where you want it.
| Originally Posted by jtostenr /img/forum/go_quote.gif I'm sure this was mentioned somewhere before, but I can't seem to find it. What is the depth of the LCDuino? How much space behind the front panel does it require? Jeff |
With the connectors I have used for attaching the momentary switch, and the connector for the programming cable, mine is about 1.25 inches from the front of the pcb to where the wires come out of the connectors on the back. The lcd sticks out about 5/16ths inch from the pcb.
How you choose to mount it, and how much space you need behind it will depend on the thickness of your front panel, and how you shim or hollow out the front panel to have the front of the lcd where you want it.
amb
Member of the Trade: AMB Laboratories
- Joined
- Apr 1, 2004
- Posts
- 4,933
- Likes
- 41
Hot on the heels of the δ1 attenuator, here is the second application module for the LCDuino-1 "system": the δ2 (delta2), a relay-based input/output selector board.
δ2 supports two channels per board, and up to eight ports per channel. Each port can be configured to be either an input port or output port by setting two jumpers. Also, not every port need to be populated. Thus, you can have an arbitrary number of input or output ports, as long as the total number of ports per channel does not exceed eight. This makes the δ2 very flexible, and could be used in a variety of pre-amplifier or headphone amplifier applications.
Similar to the δ1 attenuator, the δ2 board contains a "driver" section and a "selector" section which may optionally be snapped apart and mounted separately. In fact, the "driver" section of the δ1 and δ2 boards is identical.
The δ2 board is also the same size as the δ1, with the same mounting hole and interface/stacking connector locations, so they could all be stacked together and share the I2C bus, power supply and ground connections.
Here is a 3D rendering of the PCB:
The PCB layout (for a larger version click here):
The schematic diagram is spread over four pages. The first two pages shows the Driver and Selector sections, respectively. The third page shows an I/O port and its configuration jumpers for unbalanced and balanced applications. The fourth page is a functional block diagram showing how the δ2 might be used in a pre-amp or headphone amp.
Driver section
δ2's driver section is identical to δ1's driver section, you can read about it in this post.
Selector section
As mentioned above, there are up to eight ports per channel (Molex connectors IO0L-IO7L and IO0R-IO7R, which go to rear panel of front panel jacks). Each set of (left/right) ports can be configured as input or output by setting the JPSn and JPGn jumpers. Then, during "initial setup" of the LCDuino-1, you "tell" the firmware about the configuration.
You can configure the board to be an input selector ony (i.e., all eight ports are for input), output selector only (i.e., all eight ports are for output), or a mix of inputs and outputs. You can also populate less than 8 relays, their associated Molex jacks and parts if you don't need a total of eight ports.
The ports configured as "input" goes to their associated relays, the firmware implements a 1-of-N switching scheme (i.e., only one left/right input pair is enabled at a time). The selected input is then connected to the "input bus" (available at the Molex connectors labeled "IBUS"). In a typical preamp/headphone amp, the signal here is then "Sent" to the volume control and the active line stage/buffer or headphone amp (see page 4 of schematic above).
The ports configured as "output" also goes to their associated relays. But the firmware implements a M-of-N switching scheme for these ports (i.e., anywhere between none to all of the left/right output pairs may be enabled simultaneously). The outputs are fed from an "output bus" (via Molex connector "OBUS"). The signal here is usually "Received" from the output of the active line stage/buffer or headphone amp described above (again, see schematic page 4).
Since there is the capability to disconnect all outputs, the LCDuino-1 firmware can implement power-up delay muting (and instantaneous power-off muting) without the need for any additional hardware.
Another example δ2 application (not shown in the diagram) is a simple N-to-1-to-M signal router, where no volume control or line stage is used. The "input bus" is connected to the "output bus" (Send -> Recv), so you may choose an input to be connected to one or more outputs.
For any input port, the RTn resistor provides a load to the source when the port is not enabled. Usually a high-value resistor (10K-100K ohms) is used here to keep the source's output coupling capacitor discharged to minimize any switching "thump".
For any output port, the RTn resistor provides a low-resistance shunt to ground (as seen by the next stage, such as the input of a power amplifier). A low-value resistor (0-1K ohms) is usually appropriate here to prevent the next stage input from floating, which would act as an antenna to pick up noise. This resistor may be omitted for any port that will drive a passive load, such as headphones.
Since RTn are only "in the circuit" for disabled inputs or outputs, there is no need to use fancy resistor types for these. Due to the crowded board, there is only room for 5mm lead-spacing resistors (such as Vishay-Dale RN50, or the miniature Panasonic or Xicon 1/8W metal film resistors).
The ROUT resistors are on the output bus, and serve as optional shunt resistors for the active line stage/buffer or headphone amp output (if used). This provides a load to the line stage or headphone amp so its output will not float even when no output port is enabled. For a line stage or headphone amp with output coupling capacitor, this helps to prevent a "thump" when the output ports are switched. Depending on the design of the line stage or headphone amp, the appropriate value of this resistor can be anywhere from less than 100 ohms to tens of Kohms).
ROUT can support resistor lead spacing from 5mm-12.5mm with several intermediate sizes.
The relays are latching type, which means that the driver circuit only needs to send the coil a pulse to set the state, and then no more coil current is needed to maintain that state. To change states, a reverse polarity pulse is applied. This means that the relays will draw no current when not changing state, and will maintain their states even when power is turned off.
Note that these relays are the same type as those on the δ1, which makes them good for low-signal applications (e.g., preamp, headphone amp), but not adequate for medium or high-power speaker-level switching.
Regarding the Input/Output Configuration Jumpers
As noted above, each port has two 3P jumpers for input/output configuration. As shown on page 2 and 3 of the schematic diagram above, one of these (JPSn) is for the signal line, and routes the selected port to either the input or output bus. This jumper is what sets a port to be "input" (jumper set to 1-2) or "output" (jumper set to 2-3).
The other jumper (JPGn) sets the port's ground reference to either the input ground (IG) or the output ground (OG).
In the schematic diagram page 4 example above, it is assumed that the active line stage or headphone amp is a conventional passive-ground based design. By setting the input ports to be referenced to IG and the output ports to be referenced to OG, the two grounds connect to each other through the volume control and line stage/headphone amp, and that would work just fine.
However, when the line stage or headphone amp has an actively-driven output "ground", then care must be taken regarding which ground reference to use for each output port. For example, if a 3-channel active-ground β22 or M³ is being used as the basis for the line stage/headphone amp, the preamp-outs should be referenced to IG while the headphone-outs should be referenced to OG. See "β22 as a pre-amplifier" or "M³ as a pre-amplifier" in the "Other options" sections of their respective websites. To do so on the δ2, the JPGn jumpers for the preamp-out ports should be jumpered 1-2 (referenced to IG) while the headphone-out ports should be jumpered 2-3 (referenced to OG).
δ2 supports two channels per board, and up to eight ports per channel. Each port can be configured to be either an input port or output port by setting two jumpers. Also, not every port need to be populated. Thus, you can have an arbitrary number of input or output ports, as long as the total number of ports per channel does not exceed eight. This makes the δ2 very flexible, and could be used in a variety of pre-amplifier or headphone amplifier applications.
Similar to the δ1 attenuator, the δ2 board contains a "driver" section and a "selector" section which may optionally be snapped apart and mounted separately. In fact, the "driver" section of the δ1 and δ2 boards is identical.
The δ2 board is also the same size as the δ1, with the same mounting hole and interface/stacking connector locations, so they could all be stacked together and share the I2C bus, power supply and ground connections.
Here is a 3D rendering of the PCB:
The PCB layout (for a larger version click here):
The schematic diagram is spread over four pages. The first two pages shows the Driver and Selector sections, respectively. The third page shows an I/O port and its configuration jumpers for unbalanced and balanced applications. The fourth page is a functional block diagram showing how the δ2 might be used in a pre-amp or headphone amp.
Driver section
δ2's driver section is identical to δ1's driver section, you can read about it in this post.
Selector section
As mentioned above, there are up to eight ports per channel (Molex connectors IO0L-IO7L and IO0R-IO7R, which go to rear panel of front panel jacks). Each set of (left/right) ports can be configured as input or output by setting the JPSn and JPGn jumpers. Then, during "initial setup" of the LCDuino-1, you "tell" the firmware about the configuration.
You can configure the board to be an input selector ony (i.e., all eight ports are for input), output selector only (i.e., all eight ports are for output), or a mix of inputs and outputs. You can also populate less than 8 relays, their associated Molex jacks and parts if you don't need a total of eight ports.
The ports configured as "input" goes to their associated relays, the firmware implements a 1-of-N switching scheme (i.e., only one left/right input pair is enabled at a time). The selected input is then connected to the "input bus" (available at the Molex connectors labeled "IBUS"). In a typical preamp/headphone amp, the signal here is then "Sent" to the volume control and the active line stage/buffer or headphone amp (see page 4 of schematic above).
The ports configured as "output" also goes to their associated relays. But the firmware implements a M-of-N switching scheme for these ports (i.e., anywhere between none to all of the left/right output pairs may be enabled simultaneously). The outputs are fed from an "output bus" (via Molex connector "OBUS"). The signal here is usually "Received" from the output of the active line stage/buffer or headphone amp described above (again, see schematic page 4).
Since there is the capability to disconnect all outputs, the LCDuino-1 firmware can implement power-up delay muting (and instantaneous power-off muting) without the need for any additional hardware.
Another example δ2 application (not shown in the diagram) is a simple N-to-1-to-M signal router, where no volume control or line stage is used. The "input bus" is connected to the "output bus" (Send -> Recv), so you may choose an input to be connected to one or more outputs.
For any input port, the RTn resistor provides a load to the source when the port is not enabled. Usually a high-value resistor (10K-100K ohms) is used here to keep the source's output coupling capacitor discharged to minimize any switching "thump".
For any output port, the RTn resistor provides a low-resistance shunt to ground (as seen by the next stage, such as the input of a power amplifier). A low-value resistor (0-1K ohms) is usually appropriate here to prevent the next stage input from floating, which would act as an antenna to pick up noise. This resistor may be omitted for any port that will drive a passive load, such as headphones.
Since RTn are only "in the circuit" for disabled inputs or outputs, there is no need to use fancy resistor types for these. Due to the crowded board, there is only room for 5mm lead-spacing resistors (such as Vishay-Dale RN50, or the miniature Panasonic or Xicon 1/8W metal film resistors).
The ROUT resistors are on the output bus, and serve as optional shunt resistors for the active line stage/buffer or headphone amp output (if used). This provides a load to the line stage or headphone amp so its output will not float even when no output port is enabled. For a line stage or headphone amp with output coupling capacitor, this helps to prevent a "thump" when the output ports are switched. Depending on the design of the line stage or headphone amp, the appropriate value of this resistor can be anywhere from less than 100 ohms to tens of Kohms).
ROUT can support resistor lead spacing from 5mm-12.5mm with several intermediate sizes.
The relays are latching type, which means that the driver circuit only needs to send the coil a pulse to set the state, and then no more coil current is needed to maintain that state. To change states, a reverse polarity pulse is applied. This means that the relays will draw no current when not changing state, and will maintain their states even when power is turned off.
Note that these relays are the same type as those on the δ1, which makes them good for low-signal applications (e.g., preamp, headphone amp), but not adequate for medium or high-power speaker-level switching.
Regarding the Input/Output Configuration Jumpers
As noted above, each port has two 3P jumpers for input/output configuration. As shown on page 2 and 3 of the schematic diagram above, one of these (JPSn) is for the signal line, and routes the selected port to either the input or output bus. This jumper is what sets a port to be "input" (jumper set to 1-2) or "output" (jumper set to 2-3).
The other jumper (JPGn) sets the port's ground reference to either the input ground (IG) or the output ground (OG).
In the schematic diagram page 4 example above, it is assumed that the active line stage or headphone amp is a conventional passive-ground based design. By setting the input ports to be referenced to IG and the output ports to be referenced to OG, the two grounds connect to each other through the volume control and line stage/headphone amp, and that would work just fine.
However, when the line stage or headphone amp has an actively-driven output "ground", then care must be taken regarding which ground reference to use for each output port. For example, if a 3-channel active-ground β22 or M³ is being used as the basis for the line stage/headphone amp, the preamp-outs should be referenced to IG while the headphone-outs should be referenced to OG. See "β22 as a pre-amplifier" or "M³ as a pre-amplifier" in the "Other options" sections of their respective websites. To do so on the δ2, the JPGn jumpers for the preamp-out ports should be jumpered 1-2 (referenced to IG) while the headphone-out ports should be jumpered 2-3 (referenced to OG).
jtostenr
Head-Fier
- Joined
- Mar 28, 2009
- Posts
- 70
- Likes
- 0
Cool
Another very nice product from the AMB/Linuxworks team. However, I was disappointed to see the last sentence...
What would be the best way to adapt/incorpate speaker output switching if I was using this module?
What would be the best way to adapt/incorpate speaker output switching if I was using this module?
sachu
Headphoneus Supremus
- Joined
- Oct 29, 2006
- Posts
- 5,369
- Likes
- 155
Ti, are you looking for anymore folk to prototype this? I would surely be interested.
amb
Member of the Trade: AMB Laboratories
- Joined
- Apr 1, 2004
- Posts
- 4,933
- Likes
- 41
Quote:
Rather than using the onboard relays to switch speaker-level signals directly, you can use them to activate the coils of high-current offboard relays to do that.
Quote:
At the moment, no. But I will announce any changes if/when it happens.
| Originally Posted by jtostenr /img/forum/go_quote.gif Cool
What would be the best way to adapt/incorpate speaker output switching if I was using this module? |
Rather than using the onboard relays to switch speaker-level signals directly, you can use them to activate the coils of high-current offboard relays to do that.
Quote:
| Originally Posted by sachu Ti, are you looking for anymore folk to prototype this? I would surely be interested. |
At the moment, no. But I will announce any changes if/when it happens.
jtostenr
Head-Fier
- Joined
- Mar 28, 2009
- Posts
- 70
- Likes
- 0
Ahh, I see. Seems easy enough to do. Can't wait until you guys start selling all this LCDuino stuff
amb
Member of the Trade: AMB Laboratories
- Joined
- Apr 1, 2004
- Posts
- 4,933
- Likes
- 41
Added some more text to Post #364 above.
jtostenr
Head-Fier
- Joined
- Mar 28, 2009
- Posts
- 70
- Likes
- 0
If you were to stack 4 of these (2 Delta-1s & 2 Delta-2s) what would be the height? Would there be any reason you would not recommend stacking 4 of these? (Assuming you do all the inital config and tweaking before they are stacked.)
Ob3ron
100+ Head-Fier
- Joined
- Apr 28, 2002
- Posts
- 148
- Likes
- 0
Hey amb/linuxworks, will it be possible to make a CD player based on the LCDuino and modules? What's involved?
linuxworks
Member of the Trade: Sercona Audio
- Joined
- Oct 10, 2008
- Posts
- 3,456
- Likes
- 69
a first build: production board # 0001
8-bit build (256 steps) in half-dB increments, going from -127.5dB to 0dB.
took a good 4 hours to solder all that. maybe more than 4 hours.
8-bit build (256 steps) in half-dB increments, going from -127.5dB to 0dB.
took a good 4 hours to solder all that. maybe more than 4 hours.
amb
Member of the Trade: AMB Laboratories
- Joined
- Apr 1, 2004
- Posts
- 4,933
- Likes
- 41
Quote:
You'll need about 12-14mm spacing between each board for the pin/socket connections and to provide enough clearance for the parts. You can stack 4 boards just fine.
| Originally Posted by jtostenr /img/forum/go_quote.gif If you were to stack 4 of these (2 Delta-1s & 2 Delta-2s) what would be the height? Would there be any reason you would not recommend stacking 4 of these? (Assuming you do all the inital config and tweaking before they are stacked.) |
You'll need about 12-14mm spacing between each board for the pin/socket connections and to provide enough clearance for the parts. You can stack 4 boards just fine.
amb
Member of the Trade: AMB Laboratories
- Joined
- Apr 1, 2004
- Posts
- 4,933
- Likes
- 41
Quote:
You'd need to spin your own firmware and application module.
| Originally Posted by Ob3ron /img/forum/go_quote.gif Hey amb/linuxworks, will it be possible to make a CD player based on the LCDuino and modules? What's involved? |
You'd need to spin your own firmware and application module.
linuxworks
Member of the Trade: Sercona Audio
- Joined
- Oct 10, 2008
- Posts
- 3,456
- Likes
- 69
Quote:
do you really mean cd player or networked music player?
I have a very pre-alpha bit of code that does a network (web based) audio controller but its far from production quality. it just remotely talks to a linux MPD task and that, in turn, talks to a usb audio card ON that webserver that finally outputs audio.
that's the only work I've done on anything like this. and its not really an initial part of the project, it was just 'advanced r/d' stuff that I was toying with to get a feel of the ethernet card on the arduino platform.
audio *playback* control, while possible, isn't an initial focus of this project. at least initially.
| Originally Posted by Ob3ron /img/forum/go_quote.gif Hey amb/linuxworks, will it be possible to make a CD player based on the LCDuino and modules? What's involved? |
do you really mean cd player or networked music player?
I have a very pre-alpha bit of code that does a network (web based) audio controller but its far from production quality. it just remotely talks to a linux MPD task and that, in turn, talks to a usb audio card ON that webserver that finally outputs audio.
that's the only work I've done on anything like this. and its not really an initial part of the project, it was just 'advanced r/d' stuff that I was toying with to get a feel of the ethernet card on the arduino platform.
audio *playback* control, while possible, isn't an initial focus of this project. at least initially.
Users who are viewing this thread
