Datasheet
         71M6521DE/DH/FE Data Sheet 
Page: 76 of 107    Rev 3   
DIO_DIR1[7:6, 3:0] 
SFR91 
[7:6,3:0] 
0  0  R/W  Programs the direction of pins DIO15-DIO14, DIO11-DIO8. 1 indi-
cates output. Ignored if the pin is not configured as I/O. 
DIO_DIR2 [5:3,2:1] 
SFRA1 
[5:3,2:1] 
0 
0 
R/W 
Programs the direction of pins DIO17-DIO16 (and DIO19-DIO21 for 
the QFN package). 1 indicates output. Ignored if the pin is not con-
figured as I/O. 
DIO_0[7:4,2:0] 
SFR80 
[7:4,2:0] 
0 
0 
R/W 
The value on the pins DIO7-DIO4 and DIO2-DIO1. Pins configured 
as LCD will read zero. When written, changes data on pins confi-
gured as outputs. Pins configured as LCD or input will ignore write 
operations. The pushbutton input PB is read on DIO_0[0].  
DIO_1[7:6,3:0] 
SFR90 
[7:6,3:0] 
0 
0 
R/W 
The value on the pins DIO15-DIO14 and DIO11-DIO8. Pins con-
figured as LCD will read zero. When written, changes data on pins 
configured as outputs. Pins configured as LCD or input will ignore 
write operations.  
DIO_2[5:3,1:0] 
SFRA0 
[5:3,1:0] 
0 
0 
R/W 
The value on the pins DIO17-DIO16 (and DIO19-DIO21 for the QFN 
package). Pins configured as LCD will read zero. When written, 
changes data on pins configured as outputs. Pins configured as 
LCD or input will ignore write operations. 
DIO_EEX[1:0] 
2008[7:6] 
0  0  R/W 
When set, converts DIO4 and DIO5 to interface with external 
EEPROM. DIO4 becomes SDCK and DIO5 becomes bi-directional 
SDATA. LCD_NUM must be less than or equal to 18. 
DIO_EEX[1:0] 
Function 
00 
Disable EEPROM interface 
01 
2-Wire EEPROM interface 
10 
3-Wire EEPROM interface 
11 
--not used-- 
DIO_PV 
2008[2] 
0 
0 
R/W 
Causes VARPULSE to be output on DIO7, if DIO7 is configured as 
output. LCD_NUM must be less than 15. 
DIO_PW 
2008[3] 
0 
0 
R/W 
Causes WPULSE to be output on DIO6, if DIO6 is configured as 
output. LCD_NUM must be less than 16. 
EEDATA[7:0] 
SFR9E 
0 
0 
R/W 
Serial EEPROM interface data 
EECTRL[7:0] 
SFR9F 
0 
0 
R/W 
Serial EEPROM interface control 
ECK_DIS 
2005[5] 
0 
0 
R/W 
Emulator clock disable. When one, the emulator clock is disabled. 
This bit is to be used with caution! Inadvertently 
setting this bit will inhibit access to the part with the 
ICE interface and thus preclude flash erase and pro-
gramming operations. If ECK_DIS is set, it should be done at least 
1000ms after power-up to give emulators and programming devices 
enough time to complete an erase operation. 
EQU[2:0] 
2000[7:5] 
0 
0 
R/W 
Specifies the power equation to be used by the CE. 
EX_XFR 
EX_RTC 
EX_FWCOL 
EX_PLL 
2002[0] 
2002[1] 
2007[4] 
2007[5] 
0 
0 
0 
0 
0 
0 
0 
0 
R/W 
Interrupt enable bits. These bits enable the XFER_BUSY, the 
RTC_1SEC, the FirmWareCollision, and PLL interrupts. Note that if 
one of these interrupts is to be enabled, its corresponding EX 
enable bit must also be set. See the Interrupts section for details.  
FIR_LEN 
2005[4] 
0 
0 
R/W 
The length of the ADC decimation FIR filter.  
  1-384 cycles, 0-288 cycles 
When FIR_LEN=1, the ADC has 2.370370x higher gain. 










