Delta Tau GEO BRICK LV Reference Manual
Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables
55
I37
Additional Wait States
Range:
$000000 - $032403
Units:
Instruction cycle wait states (by bit)
Default:
$000000
I37 controls the number of wait states added to the factory default values when the Turbo PMAC
processor accesses external memory or memory-mapped I/O devices. Wait states are the number of
instruction cycles the processor idles when reading from or writing to a register of memory or I/O. On
power-up/reset, Turbo PMAC sets the number of wait states automatically based on the programmed
CPU frequency as set by I52. Under certain circumstances, particularly in accessing third-party devices,
more robust operation may be obtained by increasing the number of wait states from the factory default
values (at the cost of slightly slower operation).
processor accesses external memory or memory-mapped I/O devices. Wait states are the number of
instruction cycles the processor idles when reading from or writing to a register of memory or I/O. On
power-up/reset, Turbo PMAC sets the number of wait states automatically based on the programmed
CPU frequency as set by I52. Under certain circumstances, particularly in accessing third-party devices,
more robust operation may be obtained by increasing the number of wait states from the factory default
values (at the cost of slightly slower operation).
I37 is divided into four parts, each controlling the wait states for a different area of the memory and I/O
map. Bits 0 and 1 control the number of added wait states for I/O devices (such as ASICs and A/D
converters; dual-ported RAM also counts as an I/O device) mapped into Y-registers. Bits 16 and 17
control the number of added wait states for I/O devices mapped into X-registers. With two bits each, up
to three wait states can be added to these accesses; generally, these are both set to the same value.
map. Bits 0 and 1 control the number of added wait states for I/O devices (such as ASICs and A/D
converters; dual-ported RAM also counts as an I/O device) mapped into Y-registers. Bits 16 and 17
control the number of added wait states for I/O devices mapped into X-registers. With two bits each, up
to three wait states can be added to these accesses; generally, these are both set to the same value.
Bit 10 of I37 controls the number of added wait states for P (program, or machine-code) memory register
access. Bit 13 controls the number of added wait states for X and Y (data) memory register access. As
single-bit values, they can add only one wait state to these memory accesses. Generally, these are both
set to the same value.
access. Bit 13 controls the number of added wait states for X and Y (data) memory register access. As
single-bit values, they can add only one wait state to these memory accesses. Generally, these are both
set to the same value.
I37 is used at power-up/reset only, so to change the number of I/O wait states, change the value of I37,
issue a SAVE command, and reset the Turbo PMAC. At power-up/reset, Turbo PMAC automatically
adds the value of I37 to the value from its internal look-up table to set the number of I/O wait states. The
resulting number of wait states for different areas of the memory and I/O map is in internal CPU register
X:$FFFFFB.
issue a SAVE command, and reset the Turbo PMAC. At power-up/reset, Turbo PMAC automatically
adds the value of I37 to the value from its internal look-up table to set the number of I/O wait states. The
resulting number of wait states for different areas of the memory and I/O map is in internal CPU register
X:$FFFFFB.
Examples:
I37=$020002
; Add 2 wait states to X and Y I/O access.
I37=$002400
; Add 1 wait state to X/Y and P memory access
I37=$032403
; Add 3 wait states for I/O, 1 for memory
I38
In-Line CALL Enable
Range:
0 – 1
Units:
none
Default:
0
I38 controls the timing of the execution of a CALL command that follows motion commands on the same
program line. Normally, as soon as the program counter jumps to a new program line, as it does on a
subprogram call, program calculations are suspended until the start of execution of a new move.
program line. Normally, as soon as the program counter jumps to a new program line, as it does on a
subprogram call, program calculations are suspended until the start of execution of a new move.
If I38 is set to 1, the jump to the subprogram does not cause suspension of program calculation. This
permits some further calculations to be completed immediately following the calculation of programmed
motion. Setting I38 to 1 permits the proper use of a CREAD (coordinate read) command in a called
subroutine to store the just-computed axis move endpoints with synchronous M-variable assignments, so
that they are easily available when the move is actually being executed, facilitating calculation of data
such as “distance to go”.
permits some further calculations to be completed immediately following the calculation of programmed
motion. Setting I38 to 1 permits the proper use of a CREAD (coordinate read) command in a called
subroutine to store the just-computed axis move endpoints with synchronous M-variable assignments, so
that they are easily available when the move is actually being executed, facilitating calculation of data
such as “distance to go”.
All calculations to be completed immediately following the calculation of programmed motion must be
on the first line of the subroutine. A jump to a new line in the subroutine will suspend motion program
calculations.
on the first line of the subroutine. A jump to a new line in the subroutine will suspend motion program
calculations.