Datasheet
71M6521DE/DH/FE Data Sheet 
Rev 3    Page: 75 of 107 
I/O RAM DESCRIPTION – Alphabetical Order 
Bits with a W  (write) direction are written by the MPU into configuration RAM. Typically, they are initially stored in 
flash memory and copied to the configuration RAM by the MPU. Some of the more frequently programmed bits are 
mapped to the MPU SFR memory space. The remaining bits are mapped to the address range 0x2xxx. Bits with R 
(read) direction can be read by the MPU. Columns labeled “Rst” and “Wk” describe the bit values upon reset and 
wake, respectively. No entry in one of these columns means the bit is either read-only or is powered by the non-
volatile supply and is not initialized. Write-only bits will return zero when they are read.  
Name 
Location 
Rst 
Wk 
Dir 
Description 
ADC_E 
2005[3]  0  0  R/W  Enables ADC and VREF. When disabled, removes bias current 
BME 
2020[6] 
0 
- 
R/W 
Battery Measure Enable. When set, a load current is immediately 
applied to the battery and it is connected to the ADC to be 
measured on Alternative Mux Cycles. See MUX_ALT bit. 
CE_E 
2000[4]  0  0  R/W  CE enable. 
CE_LCTN[4:0] 
20A8[4:0] 
31 
31 
R/W 
CE program location. The starting address for the CE program is 
1024*CE_LCTN. CE_LCTN must be defined before the CE is en-
abled.  
CHOP_E[1:0] 
2002[5:4]  0  0  R/W 
Chop enable for the reference bandgap circuit. The value of CHOP 
will change on the rising edge of MUXSYNC according to the value 
in CHOP_E: 
 00-toggle
1
 01-positive 10-reversed 11-toggle 
1
except at the mux sync edge at the end of SUMCYCLE. 
CKOUT_E[1:0] 
2004[5,4] 
00  00  R/W 
CKTEST Enable. The default is 00 
00-SEG19,  
01-CK_FIR (5MHz Mission, 32kHz Brownout) 
10-Not allowed (reserved for production test) 
11-Same as 10. 
COMP_STAT[0] 
2003[0] 
--  --  R  The status of the power fail comparator for V1. 
DI_RPB[2:0] 
DIO_R1[2:0] 
DIO_R2[2:0] 
DIO_R4[2:0] 
DIO_R5[2:0] 
DIO_R6[2:0] 
DIO_R7[2:0] 
DIO_R8[2:0] 
DIO_R9[2:0] 
DIO_R10[2:0] 
DIO_R11[2:0] 
2009[2:0] 
2009[6:4] 
200A[2:0] 
200B[2:0] 
200B[6:4] 
200C[2:0] 
200C[6:4] 
200D[2:0] 
200D[6:4] 
200E[2:0] 
200E[6:4] 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
R/W 
Connects dedicated I/O pins DIO2 and DIO4 through DIO11 as well 
as input pins PB and DIO1 to internal resources. If more than one 
input is connected to the same resource, the ‘MULTIPLE’ column 
below specifies how they are combined. 
DIO_Rx 
Resource 
MULTIPLE 
000 
NONE 
-- 
001 
Reserved 
OR 
010 
T0 (Timer0 clock or gate) 
OR 
011 
T1 (Timer1 clock or gate) 
OR 
100 
High priority IO interrupt (int0 rising) 
OR 
101 
Low priority IO interrupt (int1 rising) 
OR 
110 
High priority IO interrupt (int0 falling) 
OR 
111 
Low priority IO interrupt (int1 falling) 
OR 
DIO_DIR0[7:4,2:1] 
SFRA2 
[7:4,2:0] 
0  0  R/W  Programs the direction of pins DIO7-DIO4 and DIO2-DIO1. 1 indi-
cates output. Ignored if the pin is not configured as I/O. See 
DIO_PV and DIO_PW for special option for DIO6 and DIO7 outputs. 
See DIO_EEX for special option for DIO4 and DIO5. 










