forked from Minki/linux
38 lines
2.3 KiB
Plaintext
38 lines
2.3 KiB
Plaintext
|
Programmer's View of Cpia2
|
||
|
|
|
||
|
|
Cpia2 is the second generation video coprocessor from VLSI Vision Ltd (now a
|
||
|
|
division of ST Microelectronics). There are two versions. The first is the
|
||
|
|
STV0672, which is capable of up to 30 frames per second (fps) in frame sizes
|
||
|
|
up to CIF, and 15 fps for VGA frames. The STV0676 is an improved version,
|
||
|
|
which can handle up to 30 fps VGA. Both coprocessors can be attached to two
|
||
|
|
CMOS sensors - the vvl6410 CIF sensor and the vvl6500 VGA sensor. These will
|
||
|
|
be referred to as the 410 and the 500 sensors, or the CIF and VGA sensors.
|
||
|
|
|
||
|
|
The two chipsets operate almost identically. The core is an 8051 processor,
|
||
|
|
running two different versions of firmware. The 672 runs the VP4 video
|
||
|
|
processor code, the 676 runs VP5. There are a few differences in register
|
||
|
|
mappings for the two chips. In these cases, the symbols defined in the
|
||
|
|
header files are marked with VP4 or VP5 as part of the symbol name.
|
||
|
|
|
||
|
|
The cameras appear externally as three sets of registers. Setting register
|
||
|
|
values is the only way to control the camera. Some settings are
|
||
|
|
interdependant, such as the sequence required to power up the camera. I will
|
||
|
|
try to make note of all of these cases.
|
||
|
|
|
||
|
|
The register sets are called blocks. Block 0 is the system block. This
|
||
|
|
section is always powered on when the camera is plugged in. It contains
|
||
|
|
registers that control housekeeping functions such as powering up the video
|
||
|
|
processor. The video processor is the VP block. These registers control
|
||
|
|
how the video from the sensor is processed. Examples are timing registers,
|
||
|
|
user mode (vga, qvga), scaling, cropping, framerates, and so on. The last
|
||
|
|
block is the video compressor (VC). The video stream sent from the camera is
|
||
|
|
compressed as Motion JPEG (JPEGA). The VC controls all of the compression
|
||
|
|
parameters. Looking at the file cpia2_registers.h, you can get a full view
|
||
|
|
of these registers and the possible values for most of them.
|
||
|
|
|
||
|
|
One or more registers can be set or read by sending a usb control message to
|
||
|
|
the camera. There are three modes for this. Block mode requests a number
|
||
|
|
of contiguous registers. Random mode reads or writes random registers with
|
||
|
|
a tuple structure containing address/value pairs. The repeat mode is only
|
||
|
|
used by VP4 to load a firmware patch. It contains a starting address and
|
||
|
|
a sequence of bytes to be written into a gpio port.
|