IOS-EP2 I/O SERVER MODULE Cyclone II Based FPGA Module
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Acromag, Inc. Tel:248-295-0310 Fax:248-624-9234 Email:[email protected] http://www.acromag.com
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Refer to “Program procedure to set Clock Frequency” later in this manual
for information on determining the value of these bits. A software or
hardware reset will clear this register to zero.
Clock Control Reg 3 (Read/Write)
– (Base + 1CH)
The Clock Control Register 3 is an 8-bit read/write register. This is
used as part of the control for the Cypress CY22150 Programmable Clock.
In this register only D0 (bit 0) and D7 (bit 7) are required. The other bits
(D1-D6) are not used.
The value for D0 is zero if the carrier board provides an 8MHz clock to
the FPGA. D0 is one if the carrier board provides a 32MHz signal to the
FPGA. D7 is an enable/disable signal for the CY22150 IC. Writing one to
D7 will disable the clock generator chip, including the programming function.
Setting D7 to zero will allow for normal operation. A software or hardware
reset will clear this register to zero.
Clock Trigger Register (Read/Write)
– (Base + 1EH)
The Clock Trigger Register is an 8-bit register. To initiate programming
of the Cypress CY22150 Programmable Clock with the values set in Clock
Control Registers 1, 2 and 3, write a “1” to bit 0 of this register. During
programming bit 0 will remain logic high. The programming process takes
approximately 1.2ms to complete after the initial trigger. A software or
hardware reset has no affect on this register.
Program Procedure to Set Clock Frequency
At power up the programmable clock has no valid output. The clock can
be programmed for an output frequency from 250 KHz to 100 MHz. The
clock can be programmed at any time during device operation. Program the
clock using the following process.
The program words required for Clock Control Register 1, 2, and 3 can
be calculated using a program provided by Acromag (BitCalc2K1 Version 2)
supplied with the EDK. Alternately, using the Clock Control Registers Data
Maps and the CY22150 specification sheet the necessary values can be
calculated. Cypress has a program CyberClocks available to aid with
calculations. Note that the user will have to combine the individual variables
into the control words as outlined in the register descriptions. The CY22150
Specification Sheets and CyberClocks program are available from
Cypress at
www.cypress.com
.
The reference frequency input to the Cypress CY22150 is the same as
the carrier clock, either 8MHz or 32MHz.
USER MODE