Propeller Manual

Registers – Assembly Language Reference
Registers
Each cog contains 16 special purpose registers for accessing I/O pins, the built-in counters
and video generator, and the parameter passed at the moment the cog is launched. All of
these registers are explained in the Spin Language Reference and most of the information
applies to both Spin and Propeller Assembly. The following table illustrates the 16 special
purpose registers, indicates where to find information, and states what details, if any, do not
apply to Propeller Assembly. Each of these registers can be accessed just like any other
register in the destination or source fields of instructions, except for those that are designated
with a footnote of 1 or 2. These special registers can only be read via the Source field of an
instruction; (1) they are not writable, or (2) they can not be used in the Destination field for a
read-modify-write operation.
Table 3-5: Registers
Register(s) Description
DIRA, DIRB
3
Direction Registers for 32-bit port A and 32-bit port B, see pages 289 and 104.
The optional “[Pin(s)]” parameter does not apply to Propeller Assembly; all bits of
the entire register are read/written at once, unless using the MUXx instructions.
INA
1
, INB
1,3
Input Registers for 32-bit port A and 32-bit port B (Read-Only), see pages 297 and
118. The optional “
[Pin(s)]” parameter does not apply to Propeller Assembly; all
bits of the entire register are read at once.
OUTA, OUTB
3
Output Registers for 32-bit port A and 32-bit port B, see pages 330 and 175.
The optional “[Pin(s)]” parameter does not apply to Propeller Assembly; all bits of
the entire register are read/written at once, unless using the MUXx instructions.
CNT
1
32-bit System Counter Register (Read-Only), see pages 282 and 73.
CTRA, CTRB
Counter A and Counter B Control Registers, see pages 288 and 95.
FRQA, FRQB
Counter A and Counter B Frequency Registers, see pages 293 and 111.
PHSA
2
, PHSB
2
Counter A and Counter B Phase-Locked Loop Registers, see pages 332 and 180.
VCFG
Video Configuration Register, see pages 366 and 213.
VSCL
Video Scale Register, see pages 367 and 216.
PAR
1
Cog Boot Parameter Register (Read Only), see pages 331 and 178.
Note 1: For Propeller Assembly, only accessible as a source register (i.e., mov dest, source). See the
Assembly language sections for
PAR, page 331; CNT, page 282, and INA, INB, page 297.
Note 2: For Propeller Assembly, only readable as a source register (i.e.,
mov dest, source); read
modify-write not possible as a destination register. See the Assembly language section
for PHSA, PHSB on page 332.
Note 3: Reserved for future use.
Page 338 · Propeller Manual v1.1