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09-13-2018, 12:02 PM
Hi Guys
DO NOT trust the ERC.
ERC is the check for consistency between the schematic and the board. When you lay out a circuit, you typically draw the schematic first, then press the BOARD button and Eagle asks "Create board (named as your schematic)?". OK produces the empty board outline with a field of parts and flywires to the left.
If you work on the schematic without the board open after this, the two will not be consistent and Eagle will tell you the "Forward and backward annotation will not be performed". You have to go to the board and select ERC to see the error list, which will have WARNINGS that do not mean much and ERRORS which are a problem.
In most cases, the ERC shows issues that are a problem as far as smooth board making goes. However, Eagle's ERC does NOT show all errors, such as traces crossing that should not. Supposedly, the DRC will show this.
DRC is the Design Rules Check, which uses parameters you enter for the project regarding voltage spacing. This is okay when the whole circuit operates from the same voltage, but in a tube amp or preamp there might be different voltages used for different areas. Heater trace spacing can be quite tight since it is only 6V or 12V, BUT those traces must be far from the tube plate since the plate is at high voltage. So, DRC can be cumbersome for true design rule checking but it can keep you from having crossed traces. Using DRC just for the latter means you will always have a long list of DRC "errors" that you can generally ignore but should nonetheless verify.
DO NOT trust the ERC.
ERC is the check for consistency between the schematic and the board. When you lay out a circuit, you typically draw the schematic first, then press the BOARD button and Eagle asks "Create board (named as your schematic)?". OK produces the empty board outline with a field of parts and flywires to the left.
If you work on the schematic without the board open after this, the two will not be consistent and Eagle will tell you the "Forward and backward annotation will not be performed". You have to go to the board and select ERC to see the error list, which will have WARNINGS that do not mean much and ERRORS which are a problem.
In most cases, the ERC shows issues that are a problem as far as smooth board making goes. However, Eagle's ERC does NOT show all errors, such as traces crossing that should not. Supposedly, the DRC will show this.
DRC is the Design Rules Check, which uses parameters you enter for the project regarding voltage spacing. This is okay when the whole circuit operates from the same voltage, but in a tube amp or preamp there might be different voltages used for different areas. Heater trace spacing can be quite tight since it is only 6V or 12V, BUT those traces must be far from the tube plate since the plate is at high voltage. So, DRC can be cumbersome for true design rule checking but it can keep you from having crossed traces. Using DRC just for the latter means you will always have a long list of DRC "errors" that you can generally ignore but should nonetheless verify.
