CMV300 datasheet(19/56 Pages) AMSOSRAM

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Reference:CMV300-datasheet-v2.11

CMV300 Datasheet

Page 17 of 54

Bit mode settings (address 68) : set to 8 or 10 bit mode

PLL settings (address 83): set to correct PLL range

3.8 RESET SEQUENCE

If a sensor reset is necessary while the sensor is running the following sequence should be followed.

1μs

CLK_IN

SYS_RES_N

FRAME_REQ

FIGURE 6: RESET SEQUENCE

The on-board sequencer will be reset and all programming registers will return to their default start-up values when a

falling edge is detected on the SYS_RES_N pin. After the reset there is a minimum time of 1μs needed before a

FRAME_REQ pulse can be sent. When a lower clock speed is desired while the sensor is running the reset sequence

should be executed. In this case it must be followed by a SPI upload to program the sensor for this lower clock speed.

3.9 SPI PROGRAMMING

Programming the sensor is done by writing the appropriate values to the on-board registers. These registers can be

written over a simple serial interface (SPI). The details of the timing and data format are described below. The data

written to the programming registers can also be read out over this same SPI interface.

SPI I/O’s are pulled low when not used/enabled.

3.9.1 SPI WRITE

The timing to write data over the SPI interface can be found below.

SPI_EN

SPI_IN

SPI_CLK

’1'

½ CLK

1 CLK

FIGURE 7: SPI WRITE TIMING

The data is sampled by the CMV300 on the rising edge of the SPI_CLK. The SPI_CLK has a maximum frequency of 40MHz.

The SPI_EN signal has to be high for half a clock period before the first databit is sampled. SPI_EN has to remain high for

1 clock period after the last databit is sampled. The sampled data will be written in the sequencer on the last falling

clock edge, so SPI_CLK has to go low again at the end for the write operation to be successful.

One write action contains 16 databits:



One control bit: First bit to be sent, indicates whether a read (‘0’) or write (‘1’) will occur on the SPI interface.



7 address bits: These bits form the address of the programming register that needs to be written. The address

is sent MSB first.



8 data bits: These bits form the actual data that will be written in the register selected with the address bits.

The data is written MSB first.

When several sensor registers need to be written, the timing above can be repeated with SPI_EN remaining high all the

time. See the figure below for an example of 2 registers being written in burst.

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