Don't Connect/Route Power Pin

Thanks for your reply!

For the solution, I will do as you say and change the names or manual route.

Thanks for all.

giova013  wrote:

For the solution, I will do as you say and change the names or manual route.

Changing the names of pins in library is not a good idea. That way you will have to change schematics every time you change your mind and decide to route the trace towards some of the alternative pins. For example, let's say you have Arduino which is powered with 9V via RAW input so you get 5V at several pins. If every 5V pin (which you will use to power some sensor or something) will have a different name then you will have to decide from where (from which exactly of the several possible 5V pins) you are going to route the trace in advance - during drawing schematics. If you later after switching to board view decide there is a better solution to draw the traces if you use another 5V pin, then you will have to go back to the schematics and change the connections to be able to route the trace from other 5V pin.

Similarly, if you placed Arduino board on your PCB and you are using one of the Arduino's 5V pins to directly power the board with 5V then you will have the same problem - you will have to decide which of the several 5V pins will be used to power the Arduino in advance - before having the chance to route the traces. Later when you notice it might be better to power the Arduino through one of the other 5V pins, you will have to go back to the schematics and change the connections.

On 28/10/17 10:28, Ch Ch wrote:

  wrote:

For the solution, I will do as you say and change the names or manual route.

 

Changing the names of pins in library is not a good idea. That way you will have to change schematics every time you change your mind and decide to route the trace towards some of the alternative pins. For example, let's say you have Arduino which is powered with 9V via RAW input so you get 5V at several pins. If every 5V will have a different name then you will have to decade where you are going to route the trace in advance - during drawing schematics. If you later after switching to board view decide there is a better solution to draw the traces if you use another 5V pin, then you will have to go back to the schematics and change the connections to be able to route the trace to other pin.

 

Similarly, if you placed Arduino board on your PCB and you are using one of the Arduino's 5V pins to directly power the board with 5V then you will have the same problem - you will have to decide which of the severay 5V pins will be used to power the Arduino in advance - before having the chance to route the traces. Later when you notice it might be better to power the Arduino through one of the other 5V pins, you will have to go back to the schematisc and change the connections.

 

I'm struggling to make head or tail of what you're trying to say here

but it sounds like utter tosh.

If the daughter board is being powered by 9V and the 5V pins on it are

powering other parts of the main board, it's acting like a regulator,

and all its 5V pins are outputs with parallel function. It's fine to

connect them all.

If they're all connected together and can be used to "route through"

then that's a separate issue, which was addressed, but it's not usually

good practice to do so. In any case, if you are routing through a

part, deliberately, then it's definitely good practice to SHOW THAT ON

THE SCHEMATIC, otherwise your test technician is going to be seriously

confused when debugging. Which puts us firmly in the

decide-in-advance-and-use-different-nets scenario.

On 28/10/17 10:28, Ch Ch wrote:

  wrote:

For the solution, I will do as you say and change the names or manual route.

 

Changing the names of pins in library is not a good idea. That way you will have to change schematics every time you change your mind and decide to route the trace towards some of the alternative pins. For example, let's say you have Arduino which is powered with 9V via RAW input so you get 5V at several pins. If every 5V will have a different name then you will have to decade where you are going to route the trace in advance - during drawing schematics. If you later after switching to board view decide there is a better solution to draw the traces if you use another 5V pin, then you will have to go back to the schematics and change the connections to be able to route the trace to other pin.

 

Similarly, if you placed Arduino board on your PCB and you are using one of the Arduino's 5V pins to directly power the board with 5V then you will have the same problem - you will have to decide which of the severay 5V pins will be used to power the Arduino in advance - before having the chance to route the traces. Later when you notice it might be better to power the Arduino through one of the other 5V pins, you will have to go back to the schematisc and change the connections.

 

I'm struggling to make head or tail of what you're trying to say here

but it sounds like utter tosh.

If the daughter board is being powered by 9V and the 5V pins on it are

powering other parts of the main board, it's acting like a regulator,

and all its 5V pins are outputs with parallel function. It's fine to

connect them all.

If they're all connected together and can be used to "route through"

then that's a separate issue, which was addressed, but it's not usually

good practice to do so. In any case, if you are routing through a

part, deliberately, then it's definitely good practice to SHOW THAT ON

THE SCHEMATIC, otherwise your test technician is going to be seriously

confused when debugging. Which puts us firmly in the

decide-in-advance-and-use-different-nets scenario.

autodeskguest  wrote:

I'm struggling to make head or tail of what you're trying to say here

but it sounds like utter tosh.

 

If the daughter board is being powered by 9V and the 5V pins on it are

powering other parts of the main board, it's acting like a regulator,

and all its 5V pins are outputs with parallel function. It's fine to

connect them all.

 

If they're all connected together and can be used to "route through"

then that's a separate issue, which was addressed, but it's not usually

good practice to do so. In any case, if you are routing through a

part, deliberately, then it's definitely good practice to SHOW THAT ON

THE SCHEMATIC, otherwise your test technician is going to be seriously

confused when debugging. Which puts us firmly in the

decide-in-advance-and-use-different-nets scenario.

I am saying this:

https://electronics.stackexchange.com/questions/110585/eagle-how-to-make-the-router-ignore-internally-connected-pins-in-…

English is not my native language so it might worth reading various posts regarding the same problem written by native speakers that could be found on internet.

Yes, if the daughterboard is powering other parts of the main board, it might be fine to connect all pins together. Consider this 'daughterboard', it has 5 GND pins and 2 Vcc pins. Vcc pins can be used to power the 'daughterboard' or to power something else with the 'daughterboard'.

1. If the 'daugterboard' is powered via RAW pin (going to voltage regulator) then +5V is present on both Vcc pins, ready to be used for powering some other device. The output of a voltage regulator is connected to Vcc pins.

2. If the main board already has +5V rail, then the 'daughterboard' can be powered directly through one of the Vcc pins. In that case RAW input of the 'daughterboard' is not used and daughterboard's voltage regulator is out of use. It is up to the PCB designer to decide whether to connect +5V to all of the Vcc pins or just to one of them which might be more suitable regarding the traces.

3. If the 'daughterboard' is powered via RAW pin and designer decided to power up some device using I/O pin of the microcontroller then PCB designer might decide to leave Vcc pins unconnected. For example, I have a design where I am using a voltage divider formed by a resistor and a LDR. The voltage divider is not powered from +5V but is powered from one of the I/O pins. That way I can cut the power to the voltage divider in software before putting µC to sleep so the voltage divider does not consume power during the sleep intervals.

4. There are 5 GND pins on the 'daughterboard'. GND pins near RX and TX pins are because so it is easier to connect USB --> UART converter which has very short reach of the connectors. Additional Vcc and GND pins are made for the use case when the 'daughterboard' is used as a standalone board. When that board is used as a 'daughterboard' then it is not necessary to use all of them, it is enough to use just one of the Vcc pins and just one of the GND pins. These pins are VCC@1, VCC@2, GND@1, GND@2, GND@3, GND@4 and GND@5. It is up to PCB designer to decide which one will be used and which one will not be used. Similarly there are two pairs of RS232 pins, RXI@1, RXI@2, TXO@1 and TXO@2. It is up to PCB designer to decide which RX and which TX pin is he going to use. When we use the board as a standalone then we do not connect both RX pins together on the outside of the board, we use just one of the RX pins. When we use the board as a standalone then we do not use all of the Vcc pins to power the board with +5V, we use just one of the Vcc pins to power the board and we might decide to do the same in the case the board is used as a 'daughterboard'.

Yes, it is a good practice to 'show that on the schematics' but it is up to PCB designer to decide whether he is going to use one or more pins to power the 'daughterboard'. Internally connected pins in case of the board I mentioned are interchangeable, that is - you might use just one of them or you could connect all of them even on the outside of the 'daughterboard'. If you do not want to increase the complexity of the main PCB's traces, then you will use just one of the daughterboard's Vcc pins and just one of the RX/TX pins and just one of the exposed GND pins. In that case you will have to leave some unrouted traces meaning some airwires will remain in the design. Alternatively, you might route these unwanted connections (which are forced by Eagle) in the layer which will not be sent to the manufactory. It is not up to the software to decide if you want to use one or more of the 'same' pins. Pins named as name@1, name@2, name@3, name@4, ... are already connected together and connecting the trace to any of these will connect all of them to the same net.

When the 'daugtherboard' is used as a standalone, do you connect +5V to all of the Vcc pins? No, you connect +5V to just one of them, the one which is the most suitable considering physical locations of the multiple Vcc pins. The same is for powering the 'daugterboard' or when the 'daughterboard' is powering other devices.

BTW, I cannot find this thread by browsing the forum!? I can find it only with google.