115 lines
3.3 KiB
Plaintext
115 lines
3.3 KiB
Plaintext
.include "spi.h65"
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Export spi_p, begin, end, read, pages_written, bytes_written
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.zeropage
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code_page: .res 2 ; CODE_START + pages_written * 256
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.bss
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bytes_written: .res 1
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pages_written: .res 1
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SPI_IO := spi_p::SPI_IO
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CODE_START := spi_p::CODE_START
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; spi-transferred code will be placed here
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; SPI_P = as peripheral
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.code
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.struct SPI_P_Pins
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; VIA addresses
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DDR_a .word ; address of the data direction register
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R_a .word ; address of the register
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; pin mask
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SCLK_p .byte ; Serial Clock
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POCI_p .byte ; Peripheral Out / Controller In
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PICO_p .byte ; Peripheral In / Controller Out
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CSB_p .byte ; Chip Select
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; settings
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CPOL .byte ; Clock Polarity
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CPHA .byte ; Clock Phase
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.endstruct
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;********************************************************************************
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; @function Begin listening for SPI transfers
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; @details
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; - initialize variables
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; - configure shift register to shift in under external clock
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; - enable shift register interrupts
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;********************************************************************************
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.proc begin
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stz pages_written
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stz bytes_written
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; store address in zp
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lda #<CODE_START
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sta code_page
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lda #>CODE_START
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sta code_page + 1
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; todo USE MASKS
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; set Shift register to shift in under external clock on CB1
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lda #IO::ACR::SR_SIN_PHIE
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sta SPI_IO + IO::ACR
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; enable SR interrupts
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lda #(IO::IRQ::IRQ | IO::IRQ::SR)
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sta SPI_IO + IO::IER
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; load SR to reset
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lda SPI_IO + IO::SR
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rts
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.endproc
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;********************************************************************************
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; @function Stop listening for SPI transfers
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; @details
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; Disables shift register interrupts
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; @modifies A
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;********************************************************************************
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.proc end
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; disable SR interrupts
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lda #IO::IRQ::SR
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sta SPI_IO + IO::IER
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rts
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.endproc
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;********************************************************************************
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; @function Read a byte from SPI
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; @details
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; Reads a byte from the shift register and stores it in the SPI code buffer
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; @modifies A,Y
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;********************************************************************************
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.proc read
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ldy bytes_written
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lda SPI_IO + IO::SR
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sta (code_page),y
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inc bytes_written
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beq @new_page
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rts
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@new_page:
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inc pages_written
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inc code_page + 1
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rts
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.endproc
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;********************************************************************************
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; @function Initialize the IO Adapter for SPI
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; @param ARG0-1 Address of the SPI_Pins struct
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;********************************************************************************
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;********************************************************************************
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; @function Read bytes
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; @param X Number of bytes to send
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; @param ARG0-1 Address of the SPI_Pins struct
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; @param ARG2-3 Address of the first byte
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;********************************************************************************
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.proc recv_data
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.endproc
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;********************************************************************************
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; @function Send bytes
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; @param X Number of bytes to send
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; @param ARG0-1 Address of the SPI_Pins struct
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; @param ARG2-3 Address of the first byte
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;********************************************************************************
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.proc send_data
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.endproc
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