Lattice Semiconductor Turbo Decoder User’s Guide
11
Additional Signals for External Memory
When external memory is used with this core additional signals are provided to form the interface to the external
memory. These are detailed below.
3GPP
In the case where external memory is selected, the I/O pins in Table 3 will be added to the block for exchanging
data with the memory in the case of 3GPP. It is assumed that data and parity are stored in different memory buff-
ers. Non-interleaved and interleaved parity are stored in different buffers.
Table 3. Additional I/Os Due to External Memory for 3GPP
In the case where double buffering is selected along with the external memory the I/O pins in Table 4 will also be
added to the core for exchanging data with the second buffer in the case of 3GPP.
Table 4. Additional I/Os Due to Double Buffering for 3GPP
Port Name I/O Type Width Signal Description
g1_dat_buf1 Input 3-6 Information data port 1
g2_dat_buf1 Input 3-6 Information data port 2
g1_par_odd1 Input 3-6 Parity 1 (systematic) data port 1
g2_par_odd1 Input 3-6 Parity 1 (systematic) data port 2
g1_par_even1 Input 3-6 Parity 2 (interleaved) data port 1
g2_par_even1 Input 3-6 Parity 2 (interleaved) data port 2
data_to_mem Output 3-6 Information/parity data to memory
data_waddr Output 3-6 Information/parity Write address
wren_dat_buf1 Output 1 Write enable for Information data
wren_par1_buf1 Output 1 Write enable for parity 1 (systematic)
wren_par2_buf1 Output 1 Write enable for parity 2 (interleaved)
g1_rden Output 1 Information/parity read enable port 1
g2_rden Output 1 Information/parity read enable port 2
g1_dat_raddr Output 11-15 Information read address port 1
g2_dat_raddr Output 11-15 Information read address port 2
g1_par_raddr Output 11-15 Parity read address port 1
g2_par_raddr Output 11-15 Parity read address port 2
Port Name I/O Type Width Signal Description
g1_dat_buf2 Input 3-6 Information data port 1
g2_dat_buf2 Input 3-6 Information data port 2
g1_par_odd2 Input 3-6 Parity 1 (systematic) data port 1
g2_par_odd2 Input 3-6 Parity 1 (systematic) data port 2
g1_par_even2 Input 3-6 Parity 2 (interleaved) data port 1
g2_par_even2 Input 3-6 Parity 2 (interleaved) data port 2
wren_dat_buf2 Output 1 Write enable for Information data
wren_par1_buf2 Output 1 Write enable for parity 1 (systematic)
wren_par2_buf2 Output 1 Write enable for parity 2 (interleaved)