Datasheet

AD9979
Rev. C | Page 45 of 56
Table 26. VD/HD Registers
Address
Data Bit
Content
Default
Value
Update
Type Name Description
20 [0] 0 TESTMODE Test operation only. Set to 0.
[27:1] Unused Set unused bits to 0.
21 [0] 0 SCK VDHDPOL VD/HD active polarity.
0 = active low.
1 = active high.
[2:1] 0 TESTMODE Test operation only. Set to 0.
[27:3] Unused Set unused bits to 0.
22 [27:0] 0 TESTMODE Test operation only. Set to 0.
Table 27. I/O Control Registers
Address
Data Bit
Content
Default
Value
Update
Type Name Description
23 [0] 0 SCK TESTMODE Test operation only. Set to 0.
[1] 0 TESTMODE Test operation only. Set to 0.
[2] 0 IO_NVR IOVDD voltage range for VD, HD, SCK, SDATA, and SL.
1
0 = 1.8 V.
1 = 3.3 V.
[3] 0 DATA_NVR DRVDD voltage range.
[4] 0 TESTMODE Test operation only. Set to 0.
[7:5] 1 HCLKMODE Selects HCLK output configuration (see Table 8).
[27:8] Unused Set unused bits to 0.
24 [27:0] 0 TESTMODE Test operation only. Set to 0.
25 [27:0] 0 TESTMODE Test operation only. Set to 0.
26 [27:0] 0 TESTMODE Test operation only. Set to 0.
27 [27:0] 0 TESTMODE Test operation only. Set to 0.
1
The inputs/outputs are 3 V tolerant, so there is no problem having higher than 1.8 V inputs at startup; however, this register needs to be set to 1 at initialization if
using higher than 1.8 V supplies.
Table 28. Mode Control Registers
Address
Data Bit
Content
Default
Value
Update
Type Name Description
28 [4:0] 0 VD HPATNUM Total number of H-pattern groups.
[27:5] Unused Set unused bits to 0.
29 [27:0] Unused Set unused register to 0, if accessed.
2A [2:0] 0 VD FIELDNUM Total number of fields (set to 1 for single-field operation).
[27:3] Unused Set unused bits to 0.
2B [4:0] 0 VD FIELD_SEL1 Selected first field.
[9:5] 0 FIELD_SEL2 Selected second field.
[14:10] 0 FIELD_SEL3 Selected third field.
[19:15] 0 FIELD_SEL4 Selected fourth field.
[24:20] 0 FIELD_SEL5 Selected fifth field.
[27:25] Unused Set unused bits to 0.
2C [4:0] 0 VD FIELD_SEL6 Selected sixth field.
[9:5] 0 FIELD_SEL7 Selected seventh field.
[27:10] Unused Set unused bits to 0.
2D [27:0] Unused Set unused register to 0, if accessed.
2E [27:0] Unused Set unused register to 0, if accessed.
2F [27:0] Unused Set unused register to 0, if accessed.