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Bob, Gordon and Gang, Check out? I have uploaded the schematic and its corresponding PCB layout. It has the following issues to be resolved. 1. I couldnt?find the footprint (the physical?shapes library) of the RCA connector. Instead, I have used relimate connectors?for everything. We will replace them later. 2. I coudln't find 20x4 footprint?either. so I have bunged in a 16x2 display?for the time being. Both use the same pin connector but they have different mourning?holes. 3. The Alternative TFT display's?mounting holes haven't been added either. 4. All the connectors going to the ventilator controls is to the right of the board, through relimate connectors. We could elect to go with relimate connectos?alone. However, I would like to use 3 pin connectors for the relay and 2 pin connectors for the solenoid so that one doesn't plug into the other connector.
If someone can work at getting the 20x4 and the RCA right angle connector footprints?out while I sleep, that would be great!?
Good night, all
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OK… I’ll merge our work… ? In particular, I2C level translation if not already in yours… ? Right angle RCA… Just created this:
? 
? Here’s my schematic… 
?
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From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Saturday, March 28, 2020 2:46 PM
To: [email protected]
Subject: [VentilatorDevelopers] First look, PCB ? Bob, Gordon and Gang, ? I have uploaded the schematic and its corresponding PCB layout. It has the following issues to be resolved. 1. I couldnt?find the footprint (the physical?shapes library) of the RCA connector. Instead, I have used relimate connectors?for everything. We will replace them later. 2. I coudln't find 20x4 footprint?either. so I have bunged in a 16x2 display?for the time being. Both use the same pin connector but they have different mourning?holes. 3. The Alternative TFT display's?mounting holes haven't been added either. 4. All the connectors going to the ventilator controls is to the right of the board, through relimate connectors. We could elect to go with relimate connectos?alone. However, I would like to use 3 pin connectors for the relay and 2 pin connectors for the solenoid so that one doesn't plug into the other connector. If someone can work at getting the 20x4 and the RCA right angle connector footprints?out while I sleep, that would be great!?
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The I2C is not needed. The internal pullups can be disabled in the code. We did it with Si5351 and before that with Si570 and other chips. Just the 2.2K resistors to 3.3v are enough.
On Sun 29 Mar, 2020, 3:23 AM Bob WO6W, < bobhome@...> wrote: OK… I’ll merge our work… ? In particular, I2C level translation if not already in yours… ? Right angle RCA… Just created this:
?
? Here’s my schematic…
? From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Saturday, March 28, 2020 2:46 PM
To: [email protected]
Subject: [VentilatorDevelopers] First look, PCB ? Bob, Gordon and Gang, ? I have uploaded the schematic and its corresponding PCB layout. It has the following issues to be resolved. 1. I couldnt?find the footprint (the physical?shapes library) of the RCA connector. Instead, I have used relimate connectors?for everything. We will replace them later. 2. I coudln't find 20x4 footprint?either. so I have bunged in a 16x2 display?for the time being. Both use the same pin connector but they have different mourning?holes. 3. The Alternative TFT display's?mounting holes haven't been added either. 4. All the connectors going to the ventilator controls is to the right of the board, through relimate connectors. We could elect to go with relimate connectos?alone. However, I would like to use 3 pin connectors for the relay and 2 pin connectors for the solenoid so that one doesn't plug into the other connector. If someone can work at getting the 20x4 and the RCA right angle connector footprints?out while I sleep, that would be great!?
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there was a typo in the schematic's?text box. i just fixed it. please download again. we really need to move to github now. - f
On Sun, Mar 29, 2020 at 3:26 AM Ashhar Farhan via Groups.Io <farhanbox= [email protected]> wrote: The I2C is not needed. The internal pullups can be disabled in the code. We did it with Si5351 and before that with Si570 and other chips. Just the 2.2K resistors to 3.3v are enough.
On Sun 29 Mar, 2020, 3:23 AM Bob WO6W, < bobhome@...> wrote: OK… I’ll merge our work… ? In particular, I2C level translation if not already in yours… ? Right angle RCA… Just created this:
? ![]()
? Here’s my schematic… ![]()
? From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Saturday, March 28, 2020 2:46 PM
To: [email protected]
Subject: [VentilatorDevelopers] First look, PCB ? Bob, Gordon and Gang, ? I have uploaded the schematic and its corresponding PCB layout. It has the following issues to be resolved. 1. I couldnt?find the footprint (the physical?shapes library) of the RCA connector. Instead, I have used relimate connectors?for everything. We will replace them later. 2. I coudln't find 20x4 footprint?either. so I have bunged in a 16x2 display?for the time being. Both use the same pin connector but they have different mourning?holes. 3. The Alternative TFT display's?mounting holes haven't been added either. 4. All the connectors going to the ventilator controls is to the right of the board, through relimate connectors. We could elect to go with relimate connectos?alone. However, I would like to use 3 pin connectors for the relay and 2 pin connectors for the solenoid so that one doesn't plug into the other connector. If someone can work at getting the 20x4 and the RCA right angle connector footprints?out while I sleep, that would be great!?
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Running on the edge of spec for 3.3V parts on a 5V system… But ok… ? Folks have also requested additional analog and digital ports be made available… You can easily add the 10-pin connector from my version if you choose. ? ?? 10-pin connector for additional analog and digital I/O including serial port pins ?? Input power fuse ?? (Input battery voltage / 6) provided to an analog input for monitoring the supply state ?? Test points for all DC voltages ? For now, I’ll have 20 x 4 lcd added to the RCA for you when you wake. ? I’m also leaving your design files untouched and will make my version available for you to draw from if you wish. Nothing complex and will be quick to add as you choose. ? B ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Saturday, March 28, 2020 2:56 PM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB ? The I2C is not needed. The internal pullups can be disabled in the code. We did it with Si5351 and before that with Si570 and other chips. Just the 2.2K resistors to 3.3v are enough. ? On Sun 29 Mar, 2020, 3:23 AM Bob WO6W, <bobhome@...> wrote: OK… I’ll merge our work… ? In particular, I2C level translation if not already in yours… ? Right angle RCA… Just created this: ? ? Here’s my schematic… ? From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Saturday, March 28, 2020 2:46 PM
To: [email protected]
Subject: [VentilatorDevelopers] First look, PCB ? Bob, Gordon and Gang, ? I have uploaded the schematic and its corresponding PCB layout. It has the following issues to be resolved. 1. I couldnt?find the footprint (the physical?shapes library) of the RCA connector. Instead, I have used relimate connectors?for everything. We will replace them later. 2. I coudln't find 20x4 footprint?either. so I have bunged in a 16x2 display?for the time being. Both use the same pin connector but they have different mourning?holes. 3. The Alternative TFT display's?mounting holes haven't been added either. 4. All the connectors going to the ventilator controls is to the right of the board, through relimate connectors. We could elect to go with relimate connectos?alone. However, I would like to use 3 pin connectors for the relay and 2 pin connectors for the solenoid so that one doesn't plug into the other connector. If someone can work at getting the 20x4 and the RCA right angle connector footprints?out while I sleep, that would be great!?
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Anyone github fluent? I'm not! Would like a volunteer to move the design to github.
A recognized personal shortcoming!
B
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If you gays are following my suggested UI design I have 3 buttons and a optional on/off switch.
Maybe we can have two pins connector to this switch also connected to the forth button in case we decide to use push button later on.
Suggestion: place everything in github. Shared drive get complicated to track changes. A single repo for everything (github) would be great.
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? ? Running on the edge of spec for 3.3V parts on a 5V system… But ok… ? Folks have also requested additional analog and digital ports be made available… You can easily add the 10-pin connector from my version if you choose. ? ?? 10-pin connector for additional analog and digital I/O including serial port pins ?? Input power fuse ?? (Input battery voltage / 6) provided to an analog input for monitoring the supply state ?? Test points for all DC voltages Mounting points ? For now, I’ll have 20 x 4 lcd added to the RCA for you when you wake.
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On Sat, Mar 28, 2020 at 03:48 PM, Bob WO6W wrote:
Running on the edge of spec for 3.3V parts on a 5V system… But ok…
I would make the argument to include the level shifters, to be on the safe side, as most of the uBitx applications have been pushing data. When receiving data to the Nano the voltage is just barely in spec. ---- From earlier post ---- So far everything people have been hooking up to the Nano I2C bus (displays and the synthesizer) on the uBitx have been receiving data from the Nano. In that direction the signal levels are in spec.? Because the sensors will be?predominantly doing the reverse, sending data to the Nano, would it be a good idea to include voltage level translators for the I2C bus for the 3.3/5 volt difference. ---- ----
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You can certainly do that, but I would remind you that Mr. Farhan has >three years of experience selling systems using the technique he’s telling you about, and there have been no complaints so far. ? So you may wish to add the level converter’s, that’s fine, but some people will not be able to get them. ? Consider providing a chance for jumpers across them if they don’t exist.?
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On Mar 28, 2020, at 19:35, Tom, wb6b <wb6b@...> wrote:
?On Sat, Mar 28, 2020 at 03:48 PM, Bob WO6W wrote:
Running on the edge of spec for 3.3V parts on a 5V system… But ok…
I would make the argument to include the level shifters, to be on the safe side, as most of the uBitx applications have been pushing data. When receiving data to the Nano the voltage is just barely in spec. ---- From earlier post ---- So far everything people have been hooking up to the Nano I2C bus (displays and the synthesizer) on the uBitx have been receiving data from the Nano. In that direction the signal levels are in spec.? Because the sensors will be?predominantly doing the reverse, sending data to the Nano, would it be a good idea to include voltage level translators for the I2C bus for the 3.3/5 volt difference. ---- ----
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On Sat, Mar 28, 2020 at 04:41 PM, Gordon Gibby wrote:
Consider providing a chance for jumpers across them if they don’t exist.?
I believe that is the way it wan done on the schematic I looked at in a earlier post. But, if not, that is certainly a good idea. Also, unlike the uBitx the I2C will be running over longer cable lengths to get to the sensors.? Tom, wb6b
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From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Saturday, March 28, 2020 4:42 PM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB? You can certainly do that, but I would remind you that Mr. Farhan has >three years of experience selling systems using the technique he’s telling you about, and there have been no complaints so far. ?
So you may wish to add the level converter’s, that’s fine, but some people will not be able to get them. ? Consider providing a chance for jumpers across them if they don’t exist.? ?
On Mar 28, 2020, at 19:35, Tom, wb6b <wb6b@...> wrote:
?On Sat, Mar 28, 2020 at 03:48 PM, Bob WO6W wrote: Running on the edge of spec for 3.3V parts on a 5V system… But ok…
I would make the argument to include the level shifters, to be on the safe side, as most of the uBitx applications have been pushing data. When receiving data to the Nano the voltage is just barely in spec.
---- From earlier post ----
So far everything people have been hooking up to the Nano I2C bus (displays and the synthesizer) on the uBitx have been receiving data from the Nano. In that direction the signal levels are in spec.?
Because the sensors will be?predominantly doing the reverse, sending data to the Nano, would it be a good idea to include voltage level translators for the I2C bus for the 3.3/5 volt difference.
---- ----
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Yes, good point, I don’t know what is the impact
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On Mar 28, 2020, at 19:46, Tom, wb6b <wb6b@...> wrote:
?On Sat, Mar 28, 2020 at 04:41 PM, Gordon Gibby wrote:
Consider providing a chance for jumpers across them if they don’t exist.?
I believe that is the way it wan done on the schematic I looked at in a earlier post. But, if not, that is certainly a good idea. Also, unlike the uBitx the I2C will be running over longer cable lengths to get to the sensors.? Tom, wb6b
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I2C drivers are open drain (or Open collector) as many slaves and master drive the data signal.
pullups are required (maybe interval are good enough). I would guess that most I2C interfaces work fine with either 3v3 or 5V.
level translator in a shared bus could be could be difficult to implement as all ends drive down the signal (master and all slaves).
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There’s already a Github repo for the project with the design docs, code and some mechanical&PCB design on it. The Realization branch seems to have the most recent work.? Checkout?
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On Mar 28, 2020, at 4:29 PM, Marcelo Varanda via Groups.Io < mv_email@...> wrote:
If you gays are following my suggested UI design I have 3 buttons and a optional on/off switch.
Maybe we can have two pins connector to this switch also connected to the forth button in case we decide to use push button later on.
Suggestion: place everything in github. Shared drive get complicated to track changes. A single repo for everything (github) would be great.
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OK… some pcb/schematic revisions… ? 4 x 20 LCD footprint applied to Ashhar’s pcb… This is the display Ashhar had referenced on the datasheet link for the lcd component in his schematic. The 4x20 displays that I find using the same connector as the 2 x 20 are more like 90 mm x 60 mm and would require a larger pcb. Anyway, I ran with the display he referenced. ? I also placed an RCA jack circled below… not connected to anything, just there to show the footprint. ? The RCA jack and LCD are in library file attached here:? osvent_Controller.pretty ? One last time to request that folks use the archive command in KiCad to share designs… There’s an error repeatedly tossed referencing a file in Ashhar’s home directory. The Archive command should avoid these issues… Better still a github repository when someone who knows github creates one! I’m leaving the not available reference in there… don’t want to modify the project directory references as it would probably cost Ashhar time when he goes to load it again. ? 
? ? Attached files: ?? Project library directory containing footprints for LCD and RCA jack: osvent_Controller.pretty.zip ? Two KiCad archives attached here… ? ?? Ashhar’s design with the revised LCD placed and routed, RCA placed, not connected. Component links below:? osvent_controller(2).zip ?? My earlier cut with features listed below: osvent_controllerRCL02.zip ? o?? I2C level translation… Note load options of R105, R106 bypassing the MOSFETs… Builder’s choice. Running on the edge of spec for 3.3V parts on a 5V system… I’d use the translator. o?? I also use lower value resistors on the downstream side of the I2C bus… Long lines, increased capacitance, increased exposure to noise. ?1.47K as shown adds some reliability… o?? 10-pin connector for additional analog and digital I/O including serial port pins o?? Input power fuse o?? (Input battery voltage / 6) provided to an analog input for Arduino monitoring of the supply voltage and possibly triggering alarms based on same. o?? Test points for all DC voltages o?? M3 mounting points o?? Not yet added… silkscreen field for revision of pcb, space to mark the BOM revision… ? I2C level translation: 
? ? Ashhar’s design with alternative 4x20 LCD placed and routed… placed but not connected RCA jack. RCA:? ? 4 x 20 LCD: ?I changed the LCD part number from a 3.3V version to the 5V part: From:? NHD-0420H1Z-FSW-GBW-33V3 To:????? NHD-0420H1Z-FSW-GBW
? 
?
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From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Saturday, March 28, 2020 4:42 PM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB? You can certainly do that, but I would remind you that Mr. Farhan has >three years of experience selling systems using the technique he’s telling you about, and there have been no complaints so far. ?
So you may wish to add the level converter’s, that’s fine, but some people will not be able to get them. ? Consider providing a chance for jumpers across them if they don’t exist.? ?
On Mar 28, 2020, at 19:35, Tom, wb6b <wb6b@...> wrote:
?On Sat, Mar 28, 2020 at 03:48 PM, Bob WO6W wrote: Running on the edge of spec for 3.3V parts on a 5V system… But ok…
I would make the argument to include the level shifters, to be on the safe side, as most of the uBitx applications have been pushing data. When receiving data to the Nano the voltage is just barely in spec.
---- From earlier post ----
So far everything people have been hooking up to the Nano I2C bus (displays and the synthesizer) on the uBitx have been receiving data from the Nano. In that direction the signal levels are in spec.?
Because the sensors will be?predominantly doing the reverse, sending data to the Nano, would it be a good idea to include voltage level translators for the I2C bus for the 3.3/5 volt difference.
---- ----
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On Sat, Mar 28, 2020 at 05:20 PM, Gordon Gibby wrote:
Yes, good point, I don’t know what is the impact
The better signal margin could provide some additional noise immunity and help with added capacitance when dealing with longer cable lengths.? May need to keep the I2C clock frequency at the lower frequencies supported by the devices on the bus. Possibility check sensor readings for outliers and some digital filtering in case a bit gets flipped (I'm sure the software folks are already doing this). If the cables go any distance outside the control box, a twisted pair inside a shielded cable is a good idea.? Tom, wb6b
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These are useful reference papers if you’re working with I2C… some math behind pull-up resistor values, how to level translate an I2C bus… ? ? ? I2C level translation:? I2C pull-up calculations and graphs to make life easy: ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Marcelo Varanda via Groups.Io
Sent: Saturday, March 28, 2020 5:31 PM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB ? I2C drivers are open drain (or Open collector) as many slaves and master drive the data signal.
pullups are required (maybe interval are good enough). I would guess that most I2C interfaces work fine with either 3v3 or 5V.
level translator in a shared bus could be could be difficult to implement as all ends drive down the signal (master and all slaves).
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On Sat, Mar 28, 2020 at 05:58 PM, Bob WO6W wrote:
These are useful reference papers if you’re working with I2C
Very good. Thanks...
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Hi Tom, ? I was responding to this from Marcello… ? I2C drivers are open drain (or Open collector) as many slaves and master drive the data signal.
pullups are required (maybe interval are good enough). I would guess that most I2C interfaces work fine with either 3v3 or 5V.
level translator in a shared bus could be could be difficult to implement as all ends drive down the signal (master and all slaves). ? All the best, Bob ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Tom, wb6b
Sent: Saturday, March 28, 2020 6:06 PM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB ? On Sat, Mar 28, 2020 at 05:58 PM, Bob WO6W wrote: These are useful reference papers if you’re working with I2C
Very good. Thanks...
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Marcelo Varanda