122-32000 Parallax Inc, 122-32000 Datasheet - Page 131

• 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

Exercise 9: Clock Settings
The Propeller chip’s internal clock has two speeds, slow (≈ 20 KHz) and fast (≈ 12 MHz).
Since we never specified any clock settings for our application, all previous exercises used
the Propeller chip’s default, internal RC clock in fast mode.
To specify the clock settings for the application, the top object file must set values for one or
more special constants in a
We’ll start with
180 for a listing of pre-defined symbolic values to set
with our Blinker2 object, changing the
internal slow clock (only the
{{ Blinker2.spin }}
CON
<remaining code unchanged>
Try compiling and downloading Blinker2 now.
download/boot-up process, it switches to the
Since the application is now running with a clock that is hundreds of times slower that before,
the application will run much slower, taking more than 20 seconds for the fastest toggling
pin, P20, to toggle off for the first time.
You can replace
the internal fast clock (the default).
If you’d like to use an external clock, there are many more options for
assume you’re using a 5 MHz external crystal, like the one that comes with the Propeller
Demo Board.
_CLKMODE = RCSLOW
MAXLEDS = 6
_CLKMODE
_CLKMODE = RCSLOW
first. Refer to Table 4-3: Clock Mode Setting Constants on page
CON
CON
block. These constants are:
block is shown here).
with
CON
_CLKMODE = RCFAST
'Set to internal slow clock
'Number of LED objects to use
block as follows sets the clock mode to use the
RCSLOW
clock mode and executes the application.
_CLKMODE
Once the Propeller finishes the
_CLKMODE
to have the application run with
Propeller Manual v1.0 · Page 131
to. For example, continuing
,
_CLKFREQ
_CLKMODE
and
_XINFREQ
. We’ll
.