I started out with downloading the schematics as a reference. For all components the value has been given, except for these three. Hency my question.
In the the datasheet for the ENC28J60 there is written:
The ENC28J60 is designed to operate at 25 MHz with a crystal connected to the OSC1 and OSC2 pins. The ENC28J60 design requires the use of a parallel cut crystal.
So the requency for that one is clear, but I don’t understand what they mean with parallel cut crystal.
The datasheet for the STM is more vague about the crystal; it can be between 4 and 26 Mhz, but since I plan to use the same firmware as beeing used on the Cerb.net, I guess I need the same frequency. The crystal on the Cerb I own is marked U12.000 C01J. Does this mean that it’s 12Mhz?
Since L2 is in a 0603 package, I can’t read anything of it.
To be on the safe side, it would be great if someone from GHI could provide partnumbers or specifications for these components.
From the eagle files I just downloaded from GHI, Y1, the crystal connected to ENC28J60, the value reads 25MHz.
As to the crystal connected to STM32F4, if you are going to use cerb firmware, the value should be 12MHz. From my understanding, you can simply use any 12Mhz crystal, at least that’s what I did and it worked.
I can see something is in the value field of L1, but it is all question mark, so I guess this is a coding page thing. sorry I cannot help you on this one.
One of my first MF projects was a pager server to send messages to old-style telecom pagers.
It uses a VHF transmitter to actually send the mesasages and I used chipworkx to create the POCSAG messages, calculate checksum and bit-bang them to the transmitter.
On this board, there are inputs for 10 buttons. When a button is pressed, a pre-programmed message is send to one or more pagers. I have about 40 boards running in several situations, for more than two years now without any problems!
For a new client, this set-up is to be used in an hospital, but this requires much more buttons in the entire building.
For this purpose, I have created this slave board, which will send messages over TCP to the pager server. The pagerslave has inputs for 5 buttons and outputs for 5 indicators.These will be mounted at bedside which reduces the amount of cabling required.
The whole thing is powered over ethernet by using an external POE adapter.