By now we are dealing with Inteligent Instrumentation ACQ Module Carrier Board PCI20001 w/o DMA with AD module 20023M (option
with A/DC Burr-Brown ADS7800KP s/r 333kHz ).
We managed to perform memory mapping using mmap_device_memory (since Carrier is ISA bus memory mapped device), and it
We have evaluated sample rate by means of Counter-Timer module, and realised folowing:
- it is possible to achieve declared sample & conversion time of 3 mic. sec. when we use simple operation of software
triggering and conversion status waiting.
- but when we include in loop reading two 8-bit AD registers, the lost of additional 3 micro seconds occured (approx. 1.5
micro second/register read)!!!
Our platform is x86 PC (P II Celeron 330 MHz) Neutrino 6.2.1A.
When we read other memory location outside of memory mapped region, register read time is approx. 20 nano seconds, ie 75
Is it possible to achieve faster reading of device memory map? Is it a problem with ISA bus, PC architecture in general, or
something else? (BTW, in code we are using all IRQ disabled and boosted thread priority of approx. range 60)