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robfinch |
; ============================================================================
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; __
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; \\__/ o\ (C) 2022 Robert Finch, Waterloo
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; \ __ / All rights reserved.
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; \/_// robfinch@opencores.org
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; ||
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;
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;
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; BSD 3-Clause License
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; Redistribution and use in source and binary forms, with or without
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; modification, are permitted provided that the following conditions are met:
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;
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; 1. Redistributions of source code must retain the above copyright notice, this
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; list of conditions and the following disclaimer.
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;
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; 2. Redistributions in binary form must reproduce the above copyright notice,
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; this list of conditions and the following disclaimer in the documentation
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; and/or other materials provided with the distribution.
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;
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; 3. Neither the name of the copyright holder nor the names of its
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; contributors may be used to endorse or promote products derived from
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; this software without specific prior written permission.
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;
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; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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; AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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; DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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; SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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; CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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; OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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;
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; ============================================================================
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;===============================================================================
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; Realtime clock routines
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;===============================================================================
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; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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; Read the real-time-clock chip.
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;
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; The entire contents of the clock registers and sram are read into a buffer
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; in one-shot rather than reading the registers individually.
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;
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; Parameters: none
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; Returns: d = 0 on success, otherwise non-zero
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; Modifies: d and RTCBuf
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; Stack space: 6 words
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; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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rtc_read:
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ldx #RTC
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ldy #RTCBuf
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ldb #$80
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stb I2C_CTRL,x ; enable I2C
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ldd #$900DE ; read address, write op, STA + wr bit
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bsr i2c_wr_cmd
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bitb #$80
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bne rtc_rxerr
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ldd #$10000 ; address zero, wr bit
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bsr i2c_wr_cmd
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bitb #$80
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bne rtc_rxerr
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ldd #$900DF ; read address, read op, STA + wr bit
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bsr i2c_wr_cmd
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bitb #$80
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bne rtc_rxerr
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clrb
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rtcr0001:
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lda #$20
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sta I2C_CMD,x ; rd bit
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bsr i2c_wait_tip
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bsr i2c_wait_rx_nack
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lda I2C_STAT,x
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bita #$80
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bne rtc_rxerr
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lda I2C_RXR,x
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sta b,y
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incb
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cmpb #$5F
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blo rtcr0001
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lda #$68
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sta I2C_CMD,x ; STO, rd bit + nack
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bsr i2c_wait_tip
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lda I2C_STAT,x
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bita #$80
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bne rtc_rxerr
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lda I2C_RXR,x
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sta b,y
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clrd ; return 0
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rtc_rxerr:
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clr I2C_CTRL,x ; disable I2C and return status
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clra
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rts
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; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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; Write the real-time-clock chip.
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;
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; The entire contents of the clock registers and sram are written from a
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; buffer (RTCBuf) in one-shot rather than writing the registers individually.
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;
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; Parameters: none
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; Returns: r1 = 0 on success, otherwise non-zero
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; Modifies: r1 and RTCBuf
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; Stack space: 6 words
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; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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rtc_write:
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ldx #RTC
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ldy #RTCBuf
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ldb #$80
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stb I2C_CTRL,x ; enable I2C
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ldd #$900DE ; read address, write op, STA + wr bit
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bsr i2c_wr_cmd
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bitb #$80
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bne rtc_rxerr
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ldd #$10000 ; address zero, wr bit
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bsr i2c_wr_cmd
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bitb #$80
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bne rtc_rxerr
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ldb #0
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rtcw0001:
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pshs b
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ldb b,y
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lda #$10
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bsr i2c_wr_cmd
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bitb #$80
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puls b
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bne rtc_rxerr
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incb
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cmpb #$5F
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blo rtcw0001
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ldb b,y
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lda #$50 ; STO, wr bit
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bsr i2c_wr_cmd
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bitb #$80
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bne rtc_rxerr
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clrd ; return 0
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clr I2C_CTRL,x ; disable I2C and return status
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rts
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