Front Panel Data Port
# Front Panel Data Port

The front panel data port (FPDP) is a bus that provides high speed data transfer between two or more VMEbus boards at up to 160 Mbit/s with low latency. The FPDP bus uses a 32-bit parallel synchronous bus wired with an 80-conductor ribbon cable.

The following interface functions are supported:

* FPDP/TM (transmitter master) - drives data and timing signals onto the FPDP, and also terminates the bus signals at one end of the ribbon cable
* FPDP/RM (receiver master) - receives data from the FPDP synchronously with the timing signals provided by the FPDP/TM, and also terminates the bus at the opposite end of the cable to the FPDP/TM
* FPDP/R (receiver) - receives data from the FPDP synchronously with the timing signals provided by the FPDP/TM; it does not terminate the bus. More than one FPDP/R can be connected to the FPDP bus. It can also be an alternate function to that of FPDP/RM via software control.

The connector, denoted by the FPDP specification, is a KEL P/N 8825E-080-175.

## Interface signals

* D<31:0> : Data bus driven by FPDP/TM
* DIR_n : Active low Direction signal driven by FPDP/TM
* DVALID_n: Active low data valid indication driven by FPDP/TM
* STROBE : A free running clock supplied by FPDP/TM
* NRDY_n : Active low not ready signal driven by FPDP/R or FPDP/RM. Asserted before the commencement of transfer of data by the FPDP/R or FPDP/RM asynchronous to STROBE.
* PSTROBE : Optional Differential PECL version of the STROBE driven by FPDP/TM
* SUSPEND_n : Active low suspend signal asserted by FPDP/R or FPDP/RM asynchronous to STROBE to inform the transmitter that buffer flow condition may occur. The transmitter may delay not more than 16 clocks before it suspends the data transfer.
* SYNC_n : Active low synchronization pulse provided by FPDP/TM.
* PIO1, PIO2 : Programmable I/O lines for user purposes

## Data frames

The following types of data frames are supported:

* Unframed Data
* single frame Data
* Fixed size Repeating Frame Data
* Dynamic Size Repeating Frame Data

## Cable length

FPDP interfaces work with up to a cable length of 1 meter when used in multi-drop configuration. They work up to 2 meter when using STROBE signal during point-to-point configuration. They work up to 5 meter when used with PSTROBE differential signal during point-to-point configuration.

