Maxim Integrated MAX31782 - Manual (Page 172)

  MaximIntegrated  19-7
MAX31782 User’s Guide
Revision 0; 8/11
• MOVE Acc, src (Copy data from source to active accumulator)
• MOVE dst, Acc (Copy data from active accumulator to destination)
• MOVE Acc, Acc (Recirculation of active accumulator contents)
• XCHN (Exchange nibbles within each byte of active accumulator)
• XCH (Exchange active accumulator bytes)
The active accumulator may not be the source in any instruction where it is also the implicit destination .
There is an additional notation that can be used to refer to the active accumulator for the instruction “MOVE dst, Acc .” If
the instruction is instead written as “MOVE dst, A[AP],” the source value is still the active accumulator, but no AP auto-
increment or auto-decrement function will take place, even if this function is enabled . Note that the active accumulator
may not be the destination for the MOVE dst, A[AP] instruction (i .e . MOVE Acc, A[AP] is prohibited) .
So, the two instructions
move A[7], Acc
move A[7], A[AP]
are equivalent, except that the first instruction triggers auto-inc/dec (if it is enabled), while the second one will never
do so .
The Accumulator Pointer Control Register (APC) controls the auto-inc/dec mode as well as selects the range of bits
(modulo) in the AP register that will be incremented or decremented . There are nine different unique settings for the
APC register, as listed in
Table 19-1 .
Table19-1.AccumulatorPointerControlRegisterSettings
For the modulo increment or decrement operation, the selected range of bits in AP are incremented or decremented .
However, if these bits roll over or under, they simply wrap around without affecting the remaining bits in the accumulator
pointer . So, the operations can be defined as follows:
• Increment modulo 2: AP = AP[3:1] + ((AP[0] + 1) mod 2)
• Decrement modulo 2: AP = AP[3:1] + ((AP[0] - 1) mod 2)
• Increment modulo 4: AP = AP[3:2] + ((AP[1:0] + 1) mod 4)
• Decrement modulo 4: AP = AP[3:2] + ((AP[1:0] - 1) mod 4)
• Increment modulo 8: AP = AP[3] + ((AP[2:0] + 1) mod 8)
• Decrement modulo 8: AP = AP[3] + ((AP[2:0] - 1) mod 8)
• Increment modulo 16: AP = (AP + 1) mod 16
• Decrement modulo 16: AP = (AP - 1) mod 16
APC.2(MOD2) APC.1(MOD1) APC.0(MOD0) APC.6(IDS) APC AUTOINCREMENT/DECREMENTSETTING
0 0 0 X 00h No auto-increment/decrement (default mode)
0 0 1 0 01h Increment bit 0 of AP (modulo 2)
0 0 1 1 41h Decrement bit 0 of AP (modulo 2)
0 1 0 0 02h Increment bits [1:0] of AP (modulo 4)
0 1 0 1 42h Decrement bits [1:0] of AP (modulo 4)
0 1 1 0 03h Increment bits [2:0] of AP (modulo 8)
0 1 1 1 43h Decrement bits [2:0] of AP (modulo 8)
1 0 0 0 04h Increment all 4 bits of AP (modulo 16)
1 0 0 1 44h Decrement all 4 bits of AP (modulo 16)