XM014429B datasheet(16/83 Pages) XMOS

16 / 83 page

XU6--QF6B Datasheet

on port D. If the clock is required on other tiles, then the clock should be routed to one-bit

ports on those tiles over the PCB. An output divider (Appendix D. ) can be programmed

in even steps.

xCore Tile 1

X1D11

PORT_1D

Secondary PLL

disabled

xCore Tile 1

X1D11

PORT_1D

Secondary PLL

used for app

xCore device

Figure :

Secondary

PLL

connectivity.

The secondary PLL is congured using the register documented in Appendix D. . The

output frequency of the secondary PLL is

Fpll2 = Fpll2in ×

F + 1

R + 1

OD + 1

, F and R must be chosen so that 0 ≤ R ≤ 63, 1 ≤ F ≤ 8191, 0 ≤ OD ≤ 7, and

360

MHz ≤ Fpll2in × F+1

R+1 ≤ 1800MHz. A

ag allows the user to choose between

two input frequencies, Fpll2in can be set to either the oscillator (Fosc) or the output of

the core PLL (Fcore).

The secondary PLL has an optional fractional divider (Appendix D.6). When enabled, the

fractional divider will count a period of input clocks, and over part of this period it will

cause the secondary PLL to use a divider F + 1 rather than F . The period p and fraction

are set through the control register for the fractional divider, and will result in an output

frequency:

Fpll2 = Fpll2in ×

F + 1 +

f +1

p+1

R + 1

OD + 1

The use of fractional control adds exibility to create arbitrary frequencies at the expense

of extra jitter. The fractional divider only works for f < p.

Oscillator circuit

The device has an on-chip oscillator. To use this, you need to connect a crystal, two

capacitors, and damping and feedback resistors to the device as shown in Figure

Instead of using a crystal, you can supply a V8 clock input on the XIN pin. The clock

must be running when the chip gets out of reset.

Cl2

Cl1

XIN

XOUT

xCORE

1v8

Oscillator

N.C.

xCORE

Figure

Example

circuits using

a crystal (left),

or external

oscillator

(right).

should be MΩ. Calculation of Cl1, Cl2 and Rd are beyond the scope of this datasheet,

and we recommend that you use a crystal with characteristics as specied in Table .

These have an ESR of at most 6 Ohm, have a load capacitance of

pF, and all resonate

at their fundamental frequency.

XM014429B Datasheet(PDF) 16 Page - Xmos Ltd.

XM014429B Datasheet(HTML) 16 Page - Xmos Ltd.

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

Datasheet Download

Link URL