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builderpages:plasmo:protorc1:protocf [2018/12/05 08:28]
plasmo
builderpages:plasmo:protorc1:protocf [2018/12/05 08:36] (current)
plasmo
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 ====== ProtoCF, Prototype compact flash board ====== ====== ProtoCF, Prototype compact flash board ======
  
-{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​plasmo/​protorc1/​protocf_comp.jpg?​direct&​600x342}}+[[https://​www.retrobrewcomputers.org/​lib/​exe/​fetch.php?​tok=b6ca36&​media=https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​plasmo/​protorc1/​protocf_comp.jpg|{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​plasmo/​protorc1/​protocf_comp.jpg?​direct&​600x342|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_protorc1_protocf_comp.jpg}}]]
  
-This is my modified CF prototype board. The modifications I find necessary is some setup time from CF select asserted to read/write assertion. The spec calls for 30nS setup (in mode 2). The other modification that are not strictly necessary but I find helpful is data bus serial termination (100ohm) and read signal filtering (100 ohm + 100pF RC network). The CF disks can generate significant noise when all data lines are switching that disturbs the CF read signal. If the connections are long with respect to the signal rise time, termination resistors are recommended. Terminations are less important if the CF interface is located on the same board.\\+{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​plasmo/​protorc1/​protocf_solder.jpg?​direct&​600x329}} 
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 +This is my modified CF prototype board. ​The {{:​builderpages:​plasmo:​protorc1:​protocf_scm.pdf|design}} ​ is different than the official RC2014 CF interface.  ​The modifications I find necessary is some setup time from CF select asserted to read/write assertion. The spec calls for 30nS setup (in mode 2). The other modification that are not strictly necessary but I find helpful is data bus serial termination (100ohm) and read signal filtering (100 ohm + 100pF RC network). The CF disks can generate significant noise when all data lines are switching that disturbs the CF read signal. If the connections are long with respect to the signal rise time, termination resistors are recommended. Terminations are less important if the CF interface is located on the same board.\\
 \\ \\
 I have 19 different brands of CF on hand. With this CF prototype and without termination,​ only a few (mostly the Cisco brands) would work. With termination and signal conditioning as shown in the pictures, 16 out of 19 work (by "​work",​ I mean successful PIP copy *.* with verify). However, 3 CF disks (last picture) still fail to verify. I find the SanDisk 256meg (rightmost of last picture) is the most troublesome CF disk of my collection. It fails all my designs except the Z80SBCRC.\\ I have 19 different brands of CF on hand. With this CF prototype and without termination,​ only a few (mostly the Cisco brands) would work. With termination and signal conditioning as shown in the pictures, 16 out of 19 work (by "​work",​ I mean successful PIP copy *.* with verify). However, 3 CF disks (last picture) still fail to verify. I find the SanDisk 256meg (rightmost of last picture) is the most troublesome CF disk of my collection. It fails all my designs except the Z80SBCRC.\\
 \\ \\
 There is hope, with Z80SBCRC where the CF interface is on the same board and short point-to-point wiring and without terminations or signal conditioning,​ all 19 brands of CF work. I'm hoping version 1 of ZZ80RC where CF interface is on board will perform like Z80SBCRC. There is hope, with Z80SBCRC where the CF interface is on the same board and short point-to-point wiring and without terminations or signal conditioning,​ all 19 brands of CF work. I'm hoping version 1 of ZZ80RC where CF interface is on board will perform like Z80SBCRC.
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 +CF disks that work with the above design
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 +{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​plasmo/​protorc1/​protocf_working_cf.jpg?​direct&​600x505}}
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 +----
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 +CF disks that fail with the above design
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 +{{https://​www.retrobrewcomputers.org/​lib/​plugins/​ckgedit/​fckeditor/​userfiles/​image/​builderpages/​plasmo/​protorc1/​protocf_failing_cf.jpg?​direct&​600x245}}
  
  
builderpages/plasmo/protorc1/protocf.txt · Last modified: 2018/12/05 08:36 by plasmo
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