Any time before there was a question on the forum: Can I change the filter constants in runtime ?
My answer is: Yes you can.
Here is a code snippet that complains, how it works.
void LoadFilter (uint8 fltr)// fltr is the pointer to the dedicated parameter block
{ // Put DFB RAM on the bus :
Filter_RAM_DIR_REG = Filter_RAM_DIR_BUS;
if (fltr == 1)
cymemcpy(Filter_DB_RAM,Filter100_data_b, Filter_DB_RAM_SIZE);
else if (fltr == 2)
cymemcpy(Filter_DB_RAM,Filter200_data_b, Filter_DB_RAM_SIZE);
else if (fltr == 3)
cymemcpy(Filter_DB_RAM,Filter400_data_b, Filter_DB_RAM_SIZE);
else if (fltr == 4)
cymemcpy(Filter_DB_RAM,FilterTP2800_data_b, Filter_DB_RAM_SIZE);
// Take DFB RAM off the bus :
Filter_RAM_DIR_REG = Filter_RAM_DIR_DFB;
}
The Filter_data you can compute with the embedded filter wizard. After setting your parameters
in the Filter Block, build the application an then read out the file Filter:Ram_Data.c :
const uint8 CYCODE Filter_data_b[] =
{
0x14, 0xD0, 0x01, 0x00, 0x28, 0xA0, 0x03, 0x00,...
And if you want to change the filter structure ( FIR --> IIR) you have to exchange in the same way the following matrix:
const uint8 CYCODE Filter_control[] =
{
0x20, 0x13, 0x00, 0x25, 0x61, 0x17, 0x80, 0x26,....
Don't know why all filter coefficients are located in Filter_data_b, even when you use filter stage A...
Good luck!
