Hardware and Software Design • Manufacturing Services
page 20
Address Generator Definitions
Address Generator SDRAM Start Address Registers
0080
ADD0_3
Start ADD CH 0
0084
ADD0_3
Start ADD CH 1
0088
ADD0_3
Start ADD CH 2
008C
ADD0_3
Start ADD CH 3
0180
ADD4_7
Start ADD CH 4
0184
ADD4_7
Start ADD CH 5
0188
ADD4_7
Start ADD CH 6
018C
ADD4_7
Start ADD CH 7
Read – Write
Bit#
Definition
24-0
Initial address to access SDRAM for Channel x
31-25
unused / undefined
Eight registers at different offsets with the same bit definitions provided for the 0..7 channels.
The Start register is the address to start with for accessing SDRAM. The SDRAM is organized as 64 bit words.
The addresses increment with groups of 8 bytes. To select offset 8M bytes the address would be 1M long words.
With a range of 24-0 the entire 256 Mb address space is selectable by any channel.
All transfers will start and stop on 64 bit boundaries [by hardware definition]. Smaller transfer requests will be
padded to fill a complete word. For example; if an odd number of samples is requested at the front end filter then
the data will be padded there to be on a 32 bit boundary. If the number of 32 bit words is odd then the data will be
padded onto a 64 bit boundary. There can be up to 3 samples padded in the last line of a capture.
One of the modes re-starts from the end of the last capture [address wise]. The padding occurs with each
transfer group so the next starting address will be 64 bit aligned.