122-32000 Parallax Inc, 122-32000 Datasheet - Page 206

• 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

CTRA, CTRB
– Spin Language Reference
CTRMODE
The CTRMODE field of
and
selects one of 32 operating modes, shown in Table
CTRA
CTRB
4-7, for the corresponding Counter A or Counter B. In Propeller Assembly, the CTRMODE
field can conveniently be written, along with PLLDIV, using the
instruction.
MOVI
The modes %00001 through %00011 cause
-to-
, accumulation to occur every clock
FRQx
PHSx
cycle. This creates a numerically-controlled oscillator (NCO) in PHSx[31], which feeds the
PLLx's reference input. The PLLx will multiply this frequency by 16 using its voltage-
controlled oscillator (VCO).
For stable operation, it is recommended that the VCO frequency be kept within 64 MHz to
128 MHz. This translates to an NCO frequency of 4 MHz to 8 MHz.
Using CTRA and CTRB
In Spin,
x can be read/written just like any other register or pre-defined variable. As soon
CTR
as this register is written, the new operating mode goes into effect for the counter. For
example:
CTRA := %00100 << 26
The above code sets
’s CTRMODE field to the NCO mode (%00100) and all other bits
CTRA
to zero.
Page 206 · Propeller Manual v1.0