Trying to power 100 Arduinos from single power line

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I'm trying to power up to 100 Arduinos that will be spread across a 25m wall using a single power line.



The idea is each Arduino will have a few a few buttons, leds & an oled screen and will all communicate to a master server using rs485.



====[A0]====[A1]====[A2]====[A3]====[A4]== ... ==[A99]


I've already followed this brilliant post http://www.gammon.com.au/forum/?id=11428 to implement the data connection using an rs485 bus.



However I'm struggling to understand how I could power multiple Arduinos from the one line without affecting the quality of the data bus.



Would I be able to use a 48v power rail with buck converter for each Arduino?



Would I have to isolate each Arduino and rs485 driver (my concern is the length of the wire will create different ground potential and effect the quality of the data bus)?







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  • 2




    The same question on Arduino Stack Exchange: arduino.stackexchange.com/q/55579
    – per1234
    Aug 25 at 17:08
















up vote
0
down vote

favorite
1












I'm trying to power up to 100 Arduinos that will be spread across a 25m wall using a single power line.



The idea is each Arduino will have a few a few buttons, leds & an oled screen and will all communicate to a master server using rs485.



====[A0]====[A1]====[A2]====[A3]====[A4]== ... ==[A99]


I've already followed this brilliant post http://www.gammon.com.au/forum/?id=11428 to implement the data connection using an rs485 bus.



However I'm struggling to understand how I could power multiple Arduinos from the one line without affecting the quality of the data bus.



Would I be able to use a 48v power rail with buck converter for each Arduino?



Would I have to isolate each Arduino and rs485 driver (my concern is the length of the wire will create different ground potential and effect the quality of the data bus)?







share|improve this question


















  • 2




    The same question on Arduino Stack Exchange: arduino.stackexchange.com/q/55579
    – per1234
    Aug 25 at 17:08












up vote
0
down vote

favorite
1









up vote
0
down vote

favorite
1






1





I'm trying to power up to 100 Arduinos that will be spread across a 25m wall using a single power line.



The idea is each Arduino will have a few a few buttons, leds & an oled screen and will all communicate to a master server using rs485.



====[A0]====[A1]====[A2]====[A3]====[A4]== ... ==[A99]


I've already followed this brilliant post http://www.gammon.com.au/forum/?id=11428 to implement the data connection using an rs485 bus.



However I'm struggling to understand how I could power multiple Arduinos from the one line without affecting the quality of the data bus.



Would I be able to use a 48v power rail with buck converter for each Arduino?



Would I have to isolate each Arduino and rs485 driver (my concern is the length of the wire will create different ground potential and effect the quality of the data bus)?







share|improve this question














I'm trying to power up to 100 Arduinos that will be spread across a 25m wall using a single power line.



The idea is each Arduino will have a few a few buttons, leds & an oled screen and will all communicate to a master server using rs485.



====[A0]====[A1]====[A2]====[A3]====[A4]== ... ==[A99]


I've already followed this brilliant post http://www.gammon.com.au/forum/?id=11428 to implement the data connection using an rs485 bus.



However I'm struggling to understand how I could power multiple Arduinos from the one line without affecting the quality of the data bus.



Would I be able to use a 48v power rail with buck converter for each Arduino?



Would I have to isolate each Arduino and rs485 driver (my concern is the length of the wire will create different ground potential and effect the quality of the data bus)?









share|improve this question













share|improve this question




share|improve this question








edited Aug 25 at 14:22









Neil_UK

69.2k272152




69.2k272152










asked Aug 25 at 12:35









Sam

41




41







  • 2




    The same question on Arduino Stack Exchange: arduino.stackexchange.com/q/55579
    – per1234
    Aug 25 at 17:08












  • 2




    The same question on Arduino Stack Exchange: arduino.stackexchange.com/q/55579
    – per1234
    Aug 25 at 17:08







2




2




The same question on Arduino Stack Exchange: arduino.stackexchange.com/q/55579
– per1234
Aug 25 at 17:08




The same question on Arduino Stack Exchange: arduino.stackexchange.com/q/55579
– per1234
Aug 25 at 17:08










1 Answer
1






active

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up vote
3
down vote













If your arduino is doing little more than reading buttons and comnmuniction on the RS485 bus I wouldn't worry too much about the power. At 10mA per Arduino the total consumption would be ~ 1A. Feeding at both ends would half the load. You could even feed in a couple of places in the middle.



Using buck converters would greatly reduce the currents (and the bills), so that would be a good idea if the current would be too high.



RS485 is a safe choice, but do you really need it? I think I would go for a daisy chain, where each Arduino (-nano) sends (UART output) to the next (UART input), modifying the message by insterting its own button data. With 25/100 = 0.25m between adajcent Arduino's this should be pretty reliable.



A nice extra is that the ground potential is only an issue between two adjacent Arduino's.



(I once designed such a system, which did include enumeration and bootloading. IIRC the final configuration used 30 chains of 100 nodes each.)






share|improve this answer




















  • Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
    – Sam
    Aug 25 at 13:07










  • No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
    – Wouter van Ooijen
    Aug 25 at 13:44







  • 1




    You overlooked the OLED displays. Those will substantially increase power consumption.
    – Chris Stratton
    Aug 25 at 15:07







  • 1




    "Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
    – marcelm
    Aug 25 at 15:30










  • Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
    – analogsystemsrf
    Aug 25 at 16:13










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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
3
down vote













If your arduino is doing little more than reading buttons and comnmuniction on the RS485 bus I wouldn't worry too much about the power. At 10mA per Arduino the total consumption would be ~ 1A. Feeding at both ends would half the load. You could even feed in a couple of places in the middle.



Using buck converters would greatly reduce the currents (and the bills), so that would be a good idea if the current would be too high.



RS485 is a safe choice, but do you really need it? I think I would go for a daisy chain, where each Arduino (-nano) sends (UART output) to the next (UART input), modifying the message by insterting its own button data. With 25/100 = 0.25m between adajcent Arduino's this should be pretty reliable.



A nice extra is that the ground potential is only an issue between two adjacent Arduino's.



(I once designed such a system, which did include enumeration and bootloading. IIRC the final configuration used 30 chains of 100 nodes each.)






share|improve this answer




















  • Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
    – Sam
    Aug 25 at 13:07










  • No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
    – Wouter van Ooijen
    Aug 25 at 13:44







  • 1




    You overlooked the OLED displays. Those will substantially increase power consumption.
    – Chris Stratton
    Aug 25 at 15:07







  • 1




    "Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
    – marcelm
    Aug 25 at 15:30










  • Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
    – analogsystemsrf
    Aug 25 at 16:13














up vote
3
down vote













If your arduino is doing little more than reading buttons and comnmuniction on the RS485 bus I wouldn't worry too much about the power. At 10mA per Arduino the total consumption would be ~ 1A. Feeding at both ends would half the load. You could even feed in a couple of places in the middle.



Using buck converters would greatly reduce the currents (and the bills), so that would be a good idea if the current would be too high.



RS485 is a safe choice, but do you really need it? I think I would go for a daisy chain, where each Arduino (-nano) sends (UART output) to the next (UART input), modifying the message by insterting its own button data. With 25/100 = 0.25m between adajcent Arduino's this should be pretty reliable.



A nice extra is that the ground potential is only an issue between two adjacent Arduino's.



(I once designed such a system, which did include enumeration and bootloading. IIRC the final configuration used 30 chains of 100 nodes each.)






share|improve this answer




















  • Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
    – Sam
    Aug 25 at 13:07










  • No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
    – Wouter van Ooijen
    Aug 25 at 13:44







  • 1




    You overlooked the OLED displays. Those will substantially increase power consumption.
    – Chris Stratton
    Aug 25 at 15:07







  • 1




    "Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
    – marcelm
    Aug 25 at 15:30










  • Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
    – analogsystemsrf
    Aug 25 at 16:13












up vote
3
down vote










up vote
3
down vote









If your arduino is doing little more than reading buttons and comnmuniction on the RS485 bus I wouldn't worry too much about the power. At 10mA per Arduino the total consumption would be ~ 1A. Feeding at both ends would half the load. You could even feed in a couple of places in the middle.



Using buck converters would greatly reduce the currents (and the bills), so that would be a good idea if the current would be too high.



RS485 is a safe choice, but do you really need it? I think I would go for a daisy chain, where each Arduino (-nano) sends (UART output) to the next (UART input), modifying the message by insterting its own button data. With 25/100 = 0.25m between adajcent Arduino's this should be pretty reliable.



A nice extra is that the ground potential is only an issue between two adjacent Arduino's.



(I once designed such a system, which did include enumeration and bootloading. IIRC the final configuration used 30 chains of 100 nodes each.)






share|improve this answer












If your arduino is doing little more than reading buttons and comnmuniction on the RS485 bus I wouldn't worry too much about the power. At 10mA per Arduino the total consumption would be ~ 1A. Feeding at both ends would half the load. You could even feed in a couple of places in the middle.



Using buck converters would greatly reduce the currents (and the bills), so that would be a good idea if the current would be too high.



RS485 is a safe choice, but do you really need it? I think I would go for a daisy chain, where each Arduino (-nano) sends (UART output) to the next (UART input), modifying the message by insterting its own button data. With 25/100 = 0.25m between adajcent Arduino's this should be pretty reliable.



A nice extra is that the ground potential is only an issue between two adjacent Arduino's.



(I once designed such a system, which did include enumeration and bootloading. IIRC the final configuration used 30 chains of 100 nodes each.)







share|improve this answer












share|improve this answer



share|improve this answer










answered Aug 25 at 12:45









Wouter van Ooijen

43.3k150114




43.3k150114











  • Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
    – Sam
    Aug 25 at 13:07










  • No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
    – Wouter van Ooijen
    Aug 25 at 13:44







  • 1




    You overlooked the OLED displays. Those will substantially increase power consumption.
    – Chris Stratton
    Aug 25 at 15:07







  • 1




    "Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
    – marcelm
    Aug 25 at 15:30










  • Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
    – analogsystemsrf
    Aug 25 at 16:13
















  • Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
    – Sam
    Aug 25 at 13:07










  • No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
    – Wouter van Ooijen
    Aug 25 at 13:44







  • 1




    You overlooked the OLED displays. Those will substantially increase power consumption.
    – Chris Stratton
    Aug 25 at 15:07







  • 1




    "Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
    – marcelm
    Aug 25 at 15:30










  • Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
    – analogsystemsrf
    Aug 25 at 16:13















Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
– Sam
Aug 25 at 13:07




Thanks for the reply. How did your system handle dead nodes in the chain? Would it still be feasible to do this with rs485?
– Sam
Aug 25 at 13:07












No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
– Wouter van Ooijen
Aug 25 at 13:44





No specific handling of dead nodes. Why wouid a node be (or become) dead? - RS485 can be used for point-to-point, why not, but it would be a bit overkill IMO.
– Wouter van Ooijen
Aug 25 at 13:44





1




1




You overlooked the OLED displays. Those will substantially increase power consumption.
– Chris Stratton
Aug 25 at 15:07





You overlooked the OLED displays. Those will substantially increase power consumption.
– Chris Stratton
Aug 25 at 15:07





1




1




"Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
– marcelm
Aug 25 at 15:30




"Using buck converters would greatly reduce the currents (and the bills) ..." - How would buck converters reduce the bills? You still need the same amount of power. (Also, in my experience, a non-sleeping Arduino is more like 25-30mA than 10, but that's still very manageable)
– marcelm
Aug 25 at 15:30












Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
– analogsystemsrf
Aug 25 at 16:13




Keep your GND voltage drop to about 0.1 volt; that is well within the noise margin of digital protocols. Do the same for VDD. And have a capacitor right across the GND/VDD pins of each board, so the surge currents are supplied RIGHT THERE.
– analogsystemsrf
Aug 25 at 16:13

















 

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