Maxim Integrated MAX31782 - Manual (Page 22)

MaximIntegrated 3-4
MAX31782 User’s Guide
Revision 0; 8/11
3.1SystemRegisterBitDescriptions
3.1.1AccumulatorPointerRegister(AP,8h[0h])
Initialization: This register is cleared to 00h on all forms of reset .
Access: Unrestricted direct read/write access .
3.1.2AccumulatorPointerControlRegister(APC,8h[1h])
Initialization: This register is cleared to 00h on all forms of reset .
Access: Unrestricted direct read/write access .
BIT FUNCTION
AP .[3:0]
Active Accumulator Select . These bits select which of the 16 accumulator registers are used for arithmetic and
logical operations . If the APC register has been set to perform automatic increment/decrement of the active
accumulator, this setting is automatically changed after each arithmetic or logical operation . If a ‘MOVE AP,
Acc’ instruction is executed, any enabled AP inc/dec/modulo control takes precedence over the transfer of Acc
data into AP .
AP .[7:4] Reserved . All reads return 0 .
BIT FUNCTION
APC .[2:0]
(MOD[2:0])
Accumulator Pointer Auto Increment/Decrement Modulus . If these bits are set to a nonzero value, the accumula-
tor pointer (AP[3:0]) is automatically incremented or decremented following each arithmetic or logical operation .
The mode for the auto increment/decrement is determined as follows:
MOD[2:0] AUTO INCREMENT/DECREMENT MODE
000 No auto increment/decrement (default)
001 Increment/decrement AP[0] modulo 2
010 Increment/decrement AP[1:0] modulo 4
011 Increment/decrement AP[2:0] modulo 8
100 Increment/decrement AP modulo 16
101 to 111 Reserved (modulo 16 when set)
APC .[5:3] Reserved . All reads return 0 .
APC .6 (IDS)
Increment/Decrement Select . If this bit is set to 0, the accumulator pointer AP is incremented following each
arithmetic or logical operation according to MOD[2:0] . If this bit is set to 1, the accumulator pointer AP is decre-
mented following each arithmetic or logical operation according to MOD[2:0] . If MOD[2:0] is set to 000, the set-
ting of this bit is ignored .
APC .7 (CLR)
AP Clear . Writing this bit to 1 clears the accumulator pointer AP to 0 . Once set, this bit is automatically reset to 0
by hardware . If a ‘MOVE APC, Acc’ instruction is executed requesting that AP be set to 0 (i .e ., CLR = 1), the AP
clear function overrides any enabled inc/dec/modulo control . All reads from this bit return 0 .