National Instruments AT-MIO-64F-5, User Manual

Page: 83 / 266

Chapter 3 Theory of Operation
© National Instruments Corporation 3-23 AT-MIO-64F-5 User Manual
The Am9513A 4-bit programmable frequency output channel is located at the I/O connector
FOUT pin. Any of the five internal timebases and any of the counter SOURCE or GATE inputs
can be selected as the frequency output source. The frequency output channel divides the
selected source by its 4-bit programmed value and makes the divided down signal available at
the FOUT pin.
RTSI Bus Interface Circuitry
The AT-MIO-64F-5 is interfaced to the National Instruments RTSI bus. The RTSI bus has seven
trigger lines and a system clock line. All National Instruments AT Series boards with RTSI bus
connectors can be wired together inside the PC and share these signals. A block diagram of the
RTSI bus interface circuitry is shown in Figure 3-19.
Drivers
Drivers
R
TSI Bus Connector
RTSICLK
BRDCLK
A4
DRV
A4
RCV
OUT5
OUT2
GATE1
A2
DRV
A2
RCV
B0
B1
B2
B3
B4
B5
B6
A0
A1
A2
A3
A4
A5
A6
RTSI
Switch
/SEL
DATA
OUT1
EXTTRIG
SOURCE5
EXTCONV
FOUT
Trigger
/
7
10-MHz
Oscillator
TMRTRIG
RTSI SEL
Internal
Data Bus
DAC_SDATA
DAC_SYNC
DAC_CLK
ADC_CLK
ADC_SDATA
ADC_SYNC
Figure 3-19. RTSI Bus Interface Circuitry Block Diagram
The RTSICLK line can be used to source a 10 MHz signal across the RTSI bus or to receive
another clock signal from another AT board connected to the RTSI bus. BRDCLK is the system
clock used by the AT-MIO-64F-5. Bits in a command register in the AT-MIO-64F-5 register set
control how these clock signals are routed.