Character Replacement Bug

Question

Hi, 
 github.com/.../jesd204_frame_align_replace.v 
 In the main branch for the JESD204 Interface Framework, there looks to be a bug when turning on character replacement. Everywhere I have read has been saying to turn on scrambling in order to turn on character replacement. However, it did not seem to do anything so I looked into the code. The following 2 lines of code in are in question. 
 
 library/jesd204/jesd204_common/jesd204_frame_align_replace.v

assign data_out = (cfg_disable_char_replacement || ! cfg_disable_scrambler || ENABLED == 0 ) ? data : data_replaced; 
 assign charisk_out = (IS_RX || ! cfg_disable_scrambler || cfg_disable_char_replacement || ENABLED == 0 ) ? 'b0 : char_is_align 
 
 When cfg_disable_scrambler == 1'b0 (scrambling enabled) data is always used so character replacement is not working. Something tells me this is not the intended behavior. 
 
 Sincerely, 
 Danny

AdrianC · Accepted Answer

Hello Danny, 
 We added also support for character replacement when scrambling is disabled. The module https://github.com/analogdevicesinc/hdl/blob/main/library/jesd204/jesd204_common/jesd204_frame_align_replace.v is used specifically for that. 
 For character replacement when scrambling is enabled, you don't need to replace the data path, as K28.3 is replaced with D28.3 and K28.7 si replaced with D28.7 which have the same 8bit correspondent. We are just using hdl/library/jesd204/jesd204_rx/jesd204_rx_frame_align.v at main &middot; analogdevicesinc/hdl (github.com) and hdl/library/jesd204/jesd204_tx/jesd204_tx_lane.v at main &middot; analogdevicesinc/hdl (github.com) to do character replacement when scrambling is enabled. 
 Does this make sense ? 
 I've updated the documentation. 
 Regards, 
 Adrian)