Hello Friends,
I have to read 16-bit data from Port 0 of LPC2129.But the data is not available on consecutive pins. So I assigned a name to each pin like PDB0. To read all 16 bits into a single byte I wrote the following macro to use in my code:
#define DigitalData1() (PDB0|PDB1<<1|PDB2<<2|PDB3<<3|PDB4<<4|PDB5<<5|PDB6<<6|PDB7<<7|PDB8<<8) #define DigitalData2() (PDB9<<9|PDB10<<10|PDB11<<11|PDB12<<12|PDB13<<13|PDB14<<14|PDB15<<15) #define DigitalData() ( DigitalData2() | DigitalData1())
I use DigitalData() to get the 16 bit word into a local variable like this:
ADC7606DataBuff = DigitalData();
Problem here is, this is eating good amount of time to process.
Can you suggest be what is the best way of coding to handle this kind of issues??
Thanks very much!
Please post documentation about what bits are available on what pins. Right now, we don't know your definition of PDB0, PDB1, ...
Most probably, you can make a 32-bit read, and then extract groups of bits and group-shift or send through lookup tables.
Having totally random bit orders, you can do:
uint32_t map0[256] = { ... } uint32_t map1[256] = { ... } uint32_t map2[256] = { ... } uint32-t map3[256] = { ... } uint32_t tmp = value_from_port; uint32_t value = map0[tmp & 0xff] | map1[(tmp >> 8) & 0xff] | map2[(tmp >> 16) & 0xff] | map3[tmp >> 24];
This wastes 4kB of flash space for the four lookup tables. The ((tmp >> 8) & 0xff) operation can also be replaced with an explicit 8-bit read, since many of the NXP ARM chips can read the ports as 1 32-bit register, 2 16-bit registers or 4 8-bit registers, so you get:
uint32_t value = map0[port0_byte0] | map1[port0_byte1] | map2[port0_byte2] | map3[port0_byte3];
If we know the true bit allocations, you may be able to just extract a couple of bit groups to shift left or right and merge - but we need to see in which order you mapped the pins.