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command_format.md

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MVLC command syntax

Command Args Notes
vme_read amod data_width address ['late']
vme_read_mem amod data_width address ['late']
vme_block_read amod transfers address [esst_rate]
vme_block_read_swapped amod transfers address [esst_rate]
vme_block_read_mem amod transfers address
vme_block_read_mem_swapped amod transfers address
vme_write amod data_width address value
write_marker value 32-bit marker value to insert into the output stream
write_special value 0=timestamp, 1=accu value
wait cycles 24 valid bits in units of MVLC clock cycles
signal_accu Create MVLC internal signal the current accu value.
mask_shift_accu mask shift Modify accu value. Mask first, then rotate left.
set_accu value Set the accu to a fixed value.
read_to_accu amod data_width address ['late'] VME read storing the result in the accu.
compare_loop_accu cmp value Compare accu vs given value. Loop to prev read on failure.
software_delay delay_ms
  • amod: numerical VME address modifier. Must match the transfer type. Passing a non-block amod to a block read command is an error.
  • data_width: d16 or d32.
  • esst_rate: numeric rate value. 0=160mb, 1=276mb, 2=320mb.
  • The swapped variants swap the two 32-bit words in each 64-bit word.
  • The mem variants do increment the read address. Non-mem means FIFO mode.
  • transfers is an unsigned 16-bit value, so the max transfer count for block reads is 0xffff.
  • 'late' means to read out on the trailing edge of the DTACK signal instead of at the leading edge. Required for some modules, e.g. TRIVA.

The stack accumulator

The vme_read and vme_read_mem commands usually return a single data word not contained in a block read structure. When used in combination with the MVLC stack accumulator these commands turn into block reads and produce block read output structures.

# Reads 100 times from address 0x0000.
set_accu 100
vme_read 0x09 d16 0x0000

# Reads 100 times from the device, incrementing the address after each read.
set_accu 100
vme_read_mem 0x09 d16 0x0000

In combination with read_to_accu and mask_shift_accu this can be used to read a transfer count from a module to create a fake block transfer.

signal_accu creates an MVLC internal IRQ signal using the current accu *value. This can be used to dispatch from one stack to another: read a value from a module into the accu, optionally mask_shift_accu it to exctract a trigger/IRQ number, then call *signal_accu to dispatch to the actual handler stack.

VME block read command mappings

FIFO reads do not increment the read address, mem reads do. VMEReadMem and VMEReadMemSwapped are available since MVLC firmware FW0036.

mvme VMEScript MVLC YAML MVLC command Notes
blt vme_block_read_mem 0x32 VMEReadMem
bltfifo vme_block_read 0x12 VMERead
mblt vme_block_read_mem 0x32 VMEReadMem
mbltfifo vme_block_read 0x12 VMERead
mblts vme_block_read_mem_swapped 0x33 VMEReadMemSwapped
mbltsfifo vme_block_read_swapped 0x13 VMEReadSwapped
2esst vme_block_read 0x12 VMERead for compatibility this is fifo, not mem
2esstfifo vme_block_read 0x12 VMERead same as 2esst
2esstmem vme_block_read_mem 0x32 VMEReadMem explicit mem version
2essts vme_block_read_swapped 0x13 VMEReadSwapped for compatibility this is fifo, not mem
2esstsfifo vme_block_read_swapped 0x13 VMEReadSwapped same as 2essts
2esstsmem vme_block_read_mem_swapped 0x33 VMEReadMemSwapped explicit mem version
read vme_read 0x12 VMERead MVLC stack accu + fifo flag
read vme_read_mem 0x32 VMEReadMem MVLC stack accu + mem flag

The mapping of the read command depends on whether the fifo or mem flags are specified. This is only used in combination with the MVLC stack accumulator.