![](http://datasheet.mmic.net.cn/370000/TVP3026-135_datasheet_16743199/TVP3026-135_21.png)
2–7
Table 2–7. PLL Top Level Registers
INDEX
REGISTER
0x2C
PLL address register (PAR)
0x2D
Pixel clock PLL data register (PPD)
0x2E
MCLK PLL data register (MPD)
0x2F
Loop clock PLL data register (LPD)
The PLL address register (PAR) points to the M, N, P, and status registers of each PLL. This register allows
read and write access and contains three 2-bit pointers, one for each PLL, according to the Table 2–8. Each
pointer may be programmed independently.
Table 2–8. PLL Address Register
(Index: 0x2C, Access: R/W, Default: Uninitialized)
PAR BITS
POINTER
1–0
Pixel clock PLL data register pointer
3–2
MCLK PLL data register pointer
5–4
Loop clock PLL data register pointer
Each PLL data register pointer directs its associated PLL to one of its four PLL registers according to
Table 2–9.
Table 2–9. PLL Data Register Pointer Format
BIT 1
BIT 0
REGISTER
0
0
N-value register
0
1
M-value register
1
0
P-value register
1
1
Status register (read-only)
Once the PLL data register pointers are set, the selected register is accessed through the pixel clock PLL
data register (index: 0x2D), MCLK PLL data register (index: 0x2E) or the loop clock PLL data register (index:
0x2F). The PLL data register pointer bits are independently autoincremented following a write cycle to the
corresponding PLL data register. The current state of each pointer can be identified by reading the PLL
address register (index: 0x2C). The PLL data register pointer bits do not autoincrement following a read
cycle of the PLL data registers.
The most efficient way to program the pixel clock PLL is to first write zeros to PLL address register bits
PAR(1,0) followed by three consecutive writes to the pixel clock PLL data register to program the N, M, and
P-value registers. Following the third write, the pixel clock PLL pointer will point to the read-only status
register. The status register can then be polled until the LOCK bit is set (the pointer does not autoincrement
on reads). For test purposes, the pixel clock PLL can be output on the PCLKOUT terminal by setting the
pixel clock PLL P-value register bit 6 to 1.