81 lines
2.0 KiB
NASM
81 lines
2.0 KiB
NASM
; ***************************************************************************
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; copyright : (C) 2025 by Martin Preuss
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; email : martin@libchipcard.de
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;
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; ***************************************************************************
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; * This file is part of the project "AqHome". *
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; * Please see toplevel file COPYING of that project for license details. *
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; ***************************************************************************
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#ifndef AQH_AVR_COMMON_EEPROM_R_H
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#define AQH_AVR_COMMON_EEPROM_R_H
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; ---------------------------------------------------------------------------
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; @routine Eeprom_ReadByte
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;
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; Read a byte from EEPROM (see example in ATtiny24/44/84 manual p.19).
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;
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; @param X EEPROM Address to read from
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; @return CFLAG set if address okay, cleared if out of range
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; @return R16 byte read
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; @return X EEPROM Address incremented
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; @clobbers none
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Eeprom_ReadByte:
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rcall Eeprom_CheckAddr
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brcs Eeprom_ReadByte_addrOk
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ret
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Eeprom_ReadByte_addrOk:
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; call routine with IRQs disabled
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push r15
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inr r15, SREG
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cli
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rcall Eeprom_ReadByte_noirq
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outr SREG, r15
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pop r15
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sec
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ret
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Eeprom_ReadByte_noirq:
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; wait until EEPROM ready
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Eeprom_ReadByte_waitLoop:
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.ifdef EEPE
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sbic EECR, EEPE ; wait for previous write to complete (if any)
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.else
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sbic EECR, EEWE ; wait for previous write to complete (if any)
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.endif
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rjmp Eeprom_ReadByte_waitLoop
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; read from EEPROM
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out EEARH, xh ; set EEPROM address
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out EEARL, xl
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sbi EECR, EERE ; start EEPROM read by writing EERE
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in r16, EEDR ; read data from data register
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ret
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; @end
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; ---------------------------------------------------------------------------
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; @routine Eeprom_CheckAddr
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;
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;
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; @param X EEPROM Address to validate
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; @return CFLAG set if address okay, cleared if out of range
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; @clobbers r16
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Eeprom_CheckAddr:
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mov r16, xl
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subi r16, LOW(EEPROMEND)
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mov r16, xh
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sbci r16, HIGH(EEPROMEND)
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ret
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; @end
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#endif ; AQH_AVR_COMMON_EEPROM_R_H
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