Engineering: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.

See also

• VMEbus - a computer bus standard widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987
• Serial FPDP - High-speed serial version of FPDP, that can be sent short distances over copper cables, or longer distances over optical fiber cable.