DSP with sensor i2c interface

[Gladys]

Hi all,
I have to interface DSP with 3 image sensor,s there're only two i2c
GPIO for DSP, so I need to implement an i2c core in FPGA, I've
implemented an i2c slave core to receive data from DSP and store them
with a large LUT in my FPGA and another i2c master core in FPGA to
send the stored i2c data to the 3 sensors,
Now I'm wondering if I can use FPGA as an arbitration core, what the
FPGA does is just to detect the start stop condition and the slave
address, then directly transfer the data to the right sensor without
storing in FPGA itself.
I don't know which method is better, and how to implement the second
method, could anyone give me some suggestion? Thanks

 

[Gabor]

On Jul 30, 4:47 am, Gladys <yuhu...@gmail.com> wrote:

Hi all,
 I have to interface DSP with 3 image sensor,s there're only two i2c
GPIO for DSP, so I need to implement an i2c core in FPGA, I've
implemented an i2c slave core to receive data from DSP and store them
with a large  LUT in my FPGA and another i2c master core in FPGA to
send the stored i2c data to the 3 sensors,
Now I'm wondering if I can use FPGA as an arbitration core, what the
FPGA does is just to detect the start stop condition and the slave
address, then directly transfer the data to the right sensor without
storing in FPGA itself.
I don't know which method is better, and how to implement the second
method, could anyone give me some suggestion? Thanks

There are other options. If you haven't tied down the board design
yet
you could look at I2C bus switches from NXP and others. These
devices allow a single master to access a number of sub-buses
to allow multiple parts that consume the same I2C address or
larger bus architectures that might create too much load for one
I2C segment.

Do the sensors all require the same I2C address? if not, you could
put more than one on the same bus.

Another thing I have done with FPGA's is to implement a pass-through
I2C where there is one port for the I2C master and multiple ports to
the slaves. The pass-through code flips address bits on the way
through
so each slave port sees a different address. Then to the master each
slave appears at a different location. This way the master doesn't
need to
do extra operations to switch buses.

Your master / slave approach doesn't necessarily require much
storage in the FPGA presumably you can just forward each
transaction as soon as it is sent. For read operations you can hold
off the master using SCL clock-stretching until the operation has
been forwarded to the slave.

Regards,
Gabor

 

[Gladys]

Thank you Gabor, I just found that the FPGA need to store the i2c data
and then transfer to the 3 sensor using different i2c bused at the
same time, which means the 3 sensors receive the same i2c data, so I
still need to implement and i2c slave. As the register address are in
16 bits and not continued, the register data are also in 16bits, is it
OK to use an LUT table to store the register data?

 

iam using camera fpga dsp i hav problem in sendind i2c cmd from dsp, if i use i cmd is working if u send more than 1 cmd its not working pls give soltion.
this is dsp code it send to fpga to camera control reg


int z;
*(unsigned short *)(SERVO_ADDR + 2 ) = 0x1003; //HEIGT
*(unsigned short *)(SERVO_ADDR + 4 ) =0x08;
for(z=0;z<=0xCCCC;z++);

*(unsigned short *)(SERVO_ADDR + 2 ) =0x1107; hand shake signals
*(unsigned short *)(SERVO_ADDR + 4 ) =0x1234;
for(z=0;z<=0x28F5C;z++);

*(unsigned short *)(SERVO_ADDR + 2 ) = 0x1004;//WIDTH
*(unsigned short *)(SERVO_ADDR + 4 ) =0x1004;
for(z=0;z<=0xCCCC;z++);

*(unsigned short *)(SERVO_ADDR + 2 ) = 0x1107; hand shake signal
*(unsigned short *)(SERVO_ADDR + 4 ) =0x1234;
for(z=0;z<=0x28F5C;z++);

*(unsigned short *)(SERVO_ADDR + 2 ) = 0x1005;//HB
*(unsigned short *)(SERVO_ADDR + 4 ) =0x015A;
for(z=0;z<=0xCCCC;z++);