Hello,
reviewing datasheet of NetDCU14 and comparing to datasheet of NetDCU10, we found some pins differences.
i.e: Pin J1-9 of NetDCU14 seems to be +5Vdc OUTPUT ! while equivalent pin of NetDCU10 J2-10 is named only +5Vdc (as input to my understand).
Can you tell me why ?
The only voltage inputs are NetDCU14 J1 pins 19/21/22/23 (VCFL/+5V/+5V/VBAT).
On older NetDCUs only J1 is for the power supply.
Other connectors never were meant for power supply.
Sorry but we have tested directly on CPU pins of NetDCU14.
Result: J1-9 and J1-21 both are electrically connected....
so my question is Why in the datasheet of NetDCU14 J1-9 is named as "output" and why equivalent pin in older NetDCUs are no named as "output" (so in our previous carrier design we carried +5Vdc volts power supply to these pins with no problem) ?
That's a bit confused.
Hello,
my colleges from the HW department may correct me if i am wrong. But you should never use an other connector for power supply as J1! Because here you have the noise suppression (capacitor filter ) and also routing may be optimized for surpress EMV, Out-voltage on other connectors may be used for exteral devices (e.g. LCD, I2C, SPI, serial line ...).
Hello, thats a point of view...
but if you read older NetDCU10 datasheet, pins +5Vdc and GND appears in each connector with same name that in J1 power supply, so designing our carrier we thought that supply +5Vdc and GND to these connectors was necessary because they supplied "another" different circuitry in the CPU, so supplying only J1 pins was not anought for all components ... this is the other point of view we interpret.
In the N10 datasheet is not completely clear this issue, it specifies simply "Power" in the I/O column... but now in N14 datasheet, it specifies "Power O"...
The power and GND pins on the connectors other than J1 are meant to have power available if you want to build some active circuitry around this logical connector. Then you don't need an extra power supply routed to this port. For example on the parallel interface you usually need a PLD or some similar device to handle the FS-Port protocol. If you have a carrier board for the NetDCU anyway, then it is no problem to have your own power routed to this PLD. But if you use the NetDCU as a Single Board Computer without a carrier board, then it would mean that you need a second cable from your power source to your PLD circuit, if we hadn't provided the power on the parallel port connector. But as we provide the power, you don't need this extra cable and you can use the power provided on the parallel port itself.
Up to now we thought that this idea was rather clear. But from some customer comments (similar to yours) we learned that this was not as clear as we expected and that they provided power to these pins, i.e. used them as inputs. So I guess our hardware department tried to make the intention of these pins more intuitive by adding "output". However there is (to my knowledge) no change in the power layout, so providing power through these pins should not do harm to the board. But it may have EMV and/or noise effects.
