93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
#include "PromAddressDriver.h"
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#define ADDR_CLK_HI A3
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#define ADDR_CLK_LO A4
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#define ADDR_DATA A5
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void PromAddressDriver::begin()
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{
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// The address control pins are always outputs.
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pinMode(ADDR_DATA, OUTPUT);
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pinMode(ADDR_CLK_LO, OUTPUT);
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pinMode(ADDR_CLK_HI, OUTPUT);
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digitalWrite(ADDR_DATA, LOW);
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digitalWrite(ADDR_CLK_LO, LOW);
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digitalWrite(ADDR_CLK_HI, LOW);
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DDRB |= 0x1c; // Set D10..D12 as outputs
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// To save time, the setAddress only writes the hi byte if it has changed.
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// The value used to detect the change is initialized to a non-zero value,
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// so set an initial address to avoid the the case where the first address
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// written is the 'magic' initial address.
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setAddress(0x0000);
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}
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// Set a 16 bit address in the two address shift registers and
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// the upper bits on the extened address pins.
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void PromAddressDriver::setAddress(uint32_t address)
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{
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static byte lastHi = 0xca;
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static byte lastUpper = 0xca;
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byte upper = (address >> 16) & 0xff;
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byte hi = (address >> 8) & 0xff;
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byte lo = address & 0xff;
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if (upper != lastUpper)
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{
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setUpperAddress(upper);
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lastUpper = upper;
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}
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if (hi != lastHi)
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{
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setAddressRegister(ADDR_CLK_HI, hi);
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lastHi = hi;
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}
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setAddressRegister(ADDR_CLK_LO, lo);
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}
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void PromAddressDriver::setUpperAddress(byte addr)
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{
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// Set the upper address on pins D10..D12.
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PORTB = (PORTB & 0xe3) | ((addr << 2) & 0x1c);
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}
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// Shift an 8-bit value into one of the address shift registers. Note that
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// the data pins are tied together, selecting the high or low address register
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// is a matter of using the correct clock pin to shift the data in.
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void PromAddressDriver::setAddressRegister(uint8_t clkPin, byte addr)
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{
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byte mask = 0;
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if (clkPin == ADDR_CLK_HI)
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mask = 0x08;
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else if (clkPin == ADDR_CLK_LO)
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mask = 0x10;
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// Make sure the clock is low to start.
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PORTC &= ~mask;
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// Shift 8 bits in, starting with the MSB.
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for (int ix = 0; (ix < 8); ix++)
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{
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// Set the data bit
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if (addr & 0x80)
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{
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PORTC |= 0x20;
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}
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else
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{
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PORTC &= 0xdf;
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}
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// Toggle the clock high then low
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PORTC |= mask;
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delayMicroseconds(3);
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PORTC &= ~mask;
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addr <<= 1;
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}
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}
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