This block will sniff the current value of 'x_length', but it will not modify it in any way. Hence, it assumes that the SW running in the PS has requested 8 extra bytes to accommodate the (64-bit) timestamp (i.e., 'x_length' is N+7 bytes, instead of the N-1 value described in the original ADI's 'axi_dmac' documentation).
Generics
Generic name
Type
Value
Description
DMA_LENGTH_WIDTH
integer
24
Defines the width of transfer length control register in bits; limits the maximum length of the transfers to 2^DMA_LENGTH_WIDTH (e.g., 2^24 = 16M).
Ports
Port name
Direction
Type
Description
ADCxN_clk
in
std_logic
ADC clock signal xN [depends on antenna (N = 2 for 1x1 and N = 4 for 2x2) configuration and sampling freq; max LTE value for 1x1 is @61.44 MHz and for 2x2 is @122.88 MHz]
DMA_x_length
out
std_logic_vector(DMA_LENGTH_WIDTH-1 downto 0)
Signal indicating the number of samples comprising the current DMA transfer