Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Altera_Forum
Honored Contributor I
784 Views

Cyclone V 12bit LVDS deserialisation.

Hi all, 

 

I'm interested in using the Cylcone V for a project involving an image sensor with 4 DDR LVDS channels each 12 bit encoded. I noticed, in the LVDS RX IP, 10 bit word lengths is the maximum and the input has to be connected to an LVDS pin on the FPGA. Is there anyway of chaining the SERDES or use another method to achieve 12 bit deserialisation? 

 

Thanks 

Boscoe
0 Kudos
3 Replies
Altera_Forum
Honored Contributor I
77 Views

I'm using x6 SERDES and combining 2x6Bit to 12 Bit output at half slowclock rate. 12-Bit ADC with LVDS output at 480 MHz LVDS/40 MHz output data rate. 

 

Used code as is 

 

LVDSCLK : altera_pll GENERIC MAP ( operation_mode => "lvds", reference_clock_frequency => "40.0 MHz", number_of_clocks => 4, output_clock_frequency0 => "480.0 MHz", phase_shift0 => "1041 ps", duty_cycle0 => 50, output_clock_frequency1 => "80.0 MHz", phase_shift1 => "-5208 ps", duty_cycle1 => 50, output_clock_frequency2 => "80.0 MHz", phase_shift2 => "4167 ps", duty_cycle2 => 17, output_clock_frequency3 => "40.0 MHz", phase_shift3 => "7292 ps", duty_cycle3 => 50 ) PORT MAP ( rst => reset, refclk => AD9222_FCO, outclk(0) => fastclock, -- 180° 1041 ps outclk(1) => slowclock, -- 210° -5208 ps outclk(2) => enaclock, -- 120° 4167 ps outclk(3) => outclock, locked => rx_locked ); chan: FOR I IN 0 TO N_AD_CHAN - 1 GENERATE ALTLVDS_RX_component : ALTLVDS_RX GENERIC MAP ( buffer_implementation => "RAM", cds_mode => "UNUSED", common_rx_tx_pll => "ON", data_align_rollover => 4, data_rate => "480.0 Mbps", deserialization_factor => 6, dpa_initial_phase_value => 0, dpll_lock_count => 0, dpll_lock_window => 0, enable_clock_pin_mode => "UNUSED", enable_dpa_align_to_rising_edge_only => "OFF", enable_dpa_calibration => "ON", enable_dpa_fifo => "UNUSED", enable_dpa_initial_phase_selection => "OFF", enable_dpa_mode => "OFF", enable_dpa_pll_calibration => "OFF", enable_soft_cdr_mode => "OFF", implement_in_les => "OFF", inclock_boost => 0, inclock_data_alignment => "EDGE_ALIGNED", inclock_period => 25000, inclock_phase_shift => 0, input_data_rate => 480, intended_device_family => "Cyclone V", lose_lock_on_one_change => "UNUSED", lpm_hint => "CBX_MODULE_PREFIX=lvds", lpm_type => "altlvds_rx", number_of_channels => 1, outclock_resource => "AUTO", pll_operation_mode => "NORMAL", pll_self_reset_on_loss_lock => "ON", port_rx_channel_data_align => "PORT_UNUSED", port_rx_data_align => "PORT_UNUSED", refclk_frequency => "40.000000 MHz", registered_data_align_input => "UNUSED", registered_output => "OFF", reset_fifo_at_first_lock => "UNUSED", rx_align_data_reg => "RISING_EDGE", sim_dpa_is_negative_ppm_drift => "OFF", sim_dpa_net_ppm_variation => 0, sim_dpa_output_clock_phase_shift => 0, use_coreclock_input => "OFF", use_dpll_rawperror => "OFF", use_external_pll => "ON", use_no_phase_shift => "ON", x_on_bitslip => "ON" --clk_src_is_pll => "off" ) PORT MAP ( rx_enable => enaclock, rx_in => AD9222_D(I TO I), rx_inclock => fastclock, rx_out => rx_out(I) ); PROCESS (slowclock, reset) BEGIN IF rising_edge(slowclock) THEN reg1(I) <= rx_out(I); reg2(I) <= reg1(I); reg3(I) <= reg2(I); END IF; END PROCESS; PROCESS (outclock, reset) BEGIN IF reset = '1' THEN lvds_rx(I) <= (others => '0'); ELSIF rising_edge(outclock) THEN lvds_rx(I) <= reg2(i) & reg1(i); END IF; END PROCESS;
Altera_Forum
Honored Contributor I
77 Views

 

--- Quote Start ---  

I'm using x6 SERDES and combining 2x6Bit to 12 Bit output at half slowclock rate. 12-Bit ADC with LVDS output at 480 MHz LVDS/40 MHz output data rate. 

 

Used code as is 

 

 

--- Quote End ---  

 

 

Thank you, FvM this does make sense.
Altera_Forum
Honored Contributor I
77 Views

If your data rate is reasonable you can always write your own deserializer code and make it any length you want.

Reply