ph is a program to download settings to the HELIX readout chip using the CAN field bus and Philips P82C150 SLIO. It is intended to be used by the Inner Tracker Group of HERA-B at DESY.
The HELIX bias settings and various other parameters are programmable
by a serial line protocol. This protocol is described in
[FBST
98]. For the 1998 run the HELIX PCBs are connected to
a signal distribution board which is equipped with a P82C150 SLIO.
The SLIO is a CAN bus device with 16 fully programmable digital in-
and output ports. Five of these ports are used on the signal
distribution board for the programming of the up to 12 HELIX attached
to the board. They define the signals 
,
SerClk, SerData, SerLoad and 
.
All HELIX attached to one SLIO can be loaded with identical register values simultaneously by setting commonSetBit to 1.
is kept low during programming as recommended
by [FBST98, sec. 4.9,].
In order to be able to send and receive CAN messages, a SLIO must receive special messages (so-called calibration messages) every now and then (every 8192 bits, to be precise). The sending of these messages is done by the ICAN2 modules. If a SLIO has been disconnected from the CAN bus for too long, it decalibrates and enters a sleep mode. Upon wake-up from this mode the SLIO sends a sign-on message. By default, ph waits 10 seconds for a SLIO to sign on while programming a HELIX and skips to the next entry if a timeout occurs. This timeout value can be changed on the command line using the option -t.