122-32000 Parallax Inc, 122-32000 Datasheet - Page 183

• Manufacturer Part Number: 122-32000
• Description: MANUAL PROPELLER
• Manufacturer: Parallax Inc

Specifications of 122-32000

• Accessory Type: Manual
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

CLKSET
Set both the clock mode and System Clock frequency at run time.
((PUB ┆ PRI))
Explanation
One of the most powerful features of the Propeller chip is the ability to change the clock
behavior at run time. An application can choose to toggle back and forth between a slow
clock speed (for low-power consumption) and a fast clock speed (for high-bandwidth
operations), for example.
time. It is the run-time equivalent of the
application at compile time. For example:
clkset(%01101100, 4_000_000)
This sets the clock mode to a low-speed external crystal and a Clock PLL multiplier of 2, and
indicates the resulting System Clock frequency (
command, the
that use them.
When switching from the internal clock to an external crystal, it is important to perform it as
a three-stage process:
It takes approximately 75 µs for the Propeller Chip to perform the clock source switching
action.
CLKSET
•
•
1) First set the PLLENA, OSCENA, OSCM1 and OSCM2 bits as necessary,
2) Wait for 10 ms to give the crystal time to stabilize,
3) Set the CLKSELx bits as necessary to switch the System Clock to the new source.
Mode
clock mode.
Frequency
frequency.
(Mode, Frequency)
is an integer expression that will be written to the CLK register to change the
CLKMODE
is an integer expression that indicates the resulting System Clock
and
CLKSET
CLKFREQ
is used to change the clock mode and frequency during run
commands will report the updated settings for objects
4: Spin Language Reference –
_CLKMODE
CLKFREQ
'Set to XTAL1 + PLL2x
and
_CLKFREQ
) is 4 MHz. After executing this
Propeller Manual v1.0 · Page 183
constants defined by the