Port ISO15693 codec and applications updates by ceres-c to the right branch #40
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This allows the Reader14443A.c file to be compiled successfully when the support for some card types is disabled in the Makefile
This adds automatic cloning of Mifare Ultralight cards to the selected setting. Currently, only the DUMP_MFU command existed. In order to clone a Mifare Ultralight card, the user had to convert the hex output of DUMP_MFU to binary and upload the result to the card. The CLONE_MFU command will attempt to read and store the Mifare Ultralight contents directy to the slot which is then transitioned to emulation mode. The CLONE_MFU button action does the same, so the board can be configured to clone cards by simply selecting a slot with one button and cloning with the other.
CLONE_MFU: command and button action
Docs: add documentation for CLONE_MFU button and command actions
…o epozzobon-master
While in the process of writing a new codec I stumbled upon the long standing issue of ISR sharing in AVR MCUs. Actually this is accomplished with an ISR written in C, which simply calls another plain C function referenced via a function pointer updated at runtime. This approach is slow because GCC can't optimize the ISR, since it does not know which registers will be used, so it defaults to push/pop all of them. My solution keeps the concept of pointers to functions, but greatly improves speed by reducing the ISR itself to the bare minimum to call another function, which will be compiled by GCC as a signal. This means all interrupt optimizations will be put in place by GCC, while ISRs can be still written in plain C code, but the overhead is now much smaller. It has proven to reduce by 20 the number of instructions for every ISR, mainly pushes/pops, which cuts the clock cycle count down by 30 cycles (1 cycle for every push, 2 for pop). In time units, this means 1.1 uSec are saved for every ISR invocation and every shared ISR now takes only 13 clock cycles more than the "bare" one. A new ISR_SHARED function type has been defined in Common.h to hide away from the programmer GCC attributes. All new shared interrupt handling routines should be defined of this type to prevent stack and registers corruption. Minor changes were made to Codec.h to allow including it in .S files.
Faster ISR sharing in ASM
Since GCC 10, the compiler defaults to -fno-common, thus variables with multiple tentative definitions result in linker errors. We've (me and @MrMoDDoM) extern-ed the shared variables to fix the issue. Also, when I implemented ISR sharing, somehow I forgot about a function which was shared as well, so I fixed that mistake and added a couple of comments on how shared function calls work.
Unvarying interrupt configuration moved from StartISO15693Demod to CodecInit Fixed an old issue (geo-rg#4) properly overwriting the PERBUF register when no data has to be sent Loadmodulation ISR has a new GOTO label which is called when ISO t1 time is elapsed, but data is not yet ready. This way it is possible to avoid checking for state validity on every ISR hit New inline function to clean up interrupts when field noise (garbage) is incorrectly picked up Bitrate configuration in ISO15693_EOC has been simplified Cleaned up header file with useless defines. Moved defines to .c when there was no need to share them with other source files Annotated numer of clock cycles consumed by asm ISR sharing routine As usual, this work was done with @MrMoDDoM
Removed the if-elseif in EM4233 to use a switch case which yields minor speed improvements of ~1,5 microseconds Avoid reading the UID every AppProcess tick in both EM4233 and TiTagIT to save ~11 microseconds.
ISO15693 CRC calculation is slow and it delayed too much transmission of long frames. Some readers marked transmission as unsuccesfull and ignored data. Moving CRC calculation inside the codec allows to start modulating the field while the CRC is not yet ready but, by the time it has to be trasmitted, calculation will be done. This fixes emsec#262 In EM4233, there still are issues with Read Multiple command when block locking status is requested for more than 0x1F blocks Implemented a check in ISO15693 codec to avoid out of bound CRC writes.
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This PR merges #37 to the
proxgrindbranch.As I merged the branch that #37 was based on directly, this also brings in some other small changes from official repo (such as the
CLONE_MFUcommand). If requested I can re-do this PR and just port the relevant commits.