AD9920ABBCZ datasheet(68/112 Pages) AD

68 / 112 page

AD9920A

Rev. B | Page 68 of 112

GP LOOKUP TABLE (LUT)

The AD9920A is equipped with a lookup table for each pair

of consecutive GP signals when configured as outputs. GPO1 is

always combined with GPO2, GPO3 is always combined with

GPO4, GPO5 is always combined with GPO6, and GPO7 is

always combined with GPO8. The external GPO outputs from

each pair can output the result of the LUT or the original GP

internal signal.

GP1

LUT

GPO2

GPO1

GP2

GP2_USE_LUT

GP1_USE_LUT

Figure 88. Internal LUT for GPO1 and GPO2 Signals

Address 0x7B configures the behavior of the LUT and which

signals receive the result. Each 4-bit LUT_FOR_GPxy register

can realize any logic combination of GPx and GPy. For example,

Table 46 shows how the register values of LUT_FOR_GP12,

Bits[11:8], are determined. XOR, NAND, AND, and OR results

are shown, but any 4-bit combination is possible. A simple

example of XOR gating is shown in Figure 89.

Table 46. LUT Results Based on GP1 and GP2 Values

GP2

GP1

LUT: XOR

LUT: NAND

LUT: AND

LUT: OR

GP1

GP2

GPO2

NOTES

1. LOGIC COMBINATION (XOR) OF PROGRAMMED TOGGLES

GP1 AND GP2.

LUT_FOR_GP12[11:8] = 0x06

GP2_USE_LUT = 1

GP1_USE_LUT = 0

GPO1

Figure 89. LUT Example for GP1 XOR GP2

Field Counter and GPO Limitations

The following is a summary of the known limitations of the

field counters and GPO signals.

•

The field counter trigger (PRIMARY_ACTION and

SECOND_ACTION registers, Address 0x70) is

automatically reset at the start of every VD period.

Therefore, there must be one VD period between

sequential programming to that address.

•

If GPx_PROTOCOL = 1, it must be manually reset to

GPx_PROTOCOL = 0 one VD period before it can be

used again. If manual toggles are desired in sequential

fields, the MANUAL_TRIG register should be used in

conjunction with GPx_PROTOCOL = 1.

AD9920ABBCZ Datasheet(PDF) 68 Page - Analog Devices

AD9920ABBCZ Datasheet(HTML) 68 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL