Delta Tau Turbo PMAC Clipper, Hardware Reference Manual

Page: 64 / 84

Turbo PMAC Clipper Hardware Reference Manual
Laser Control Output 64
The following logic circuit is programmed as the Option-11A into the Lattice chip:
As you can see, the idea is to switch the output between PWM_B signal and PFM signal based upon
either of the EQU outputs. EQU outputs are fast responding outputs which can either be activated
manually or based upon position compare feature of the PMAC. CTRL outputs control which of the
EQUs or what combination of EQUs will be used to control the output mode.
As an example, if a user wants to use EQU1 to switch between the Tickle pulse (PFM) and Output mode
(PWM), then CTRL0 must be turned on. As a safety measure, no output will be generated unless at least
one of the CTRL outputs is set to 1.
Clock Settings
The clock used for PWM is related to the Max Phase Clock, which is used to generate the Phase and
Servo clock, selecting an appropriate PWM frequency which satisfies both the laser requirements and
servo requirements can be challenging, especially if user is trying to use Filtered PWM outputs as DAC
outputs for amplifier commands.
In most of the applications, the PWM frequency is a set value and is not change at all, however in some
applications this is not the case and the PWM has to change based upon the material being cut or worked
on. If you are required to change the PWM based upon the material, you won’t be able to use the filtered
PWM outputs directly available from the Clipper board and you have to use ACC-8ES (Analog Servo
Interface) in order to get the DAC outputs for servo amplifier commands.
If the PWM frequency required for the laser is less than 30kHz required for the Filtered PWM outputs,
which mostly is the case, then the PWM frequency of the DSPGate1 (30kHz) should be divisible by
PWM frequency of the DSPGate2 which is used for generating the laser output signal. The clock source
on the Clipper, by default, is the DSPGate1, which in this case needs to be changed to DSPGate2. In order
to change the clock source, the following steps should be followed carefully in exact explained order or
else you may cause a watchdog.
Switching the clock source:
1. Set I19=6807 .