TommyPROM/HardwareVerify/PromAddressDriver.cpp

105 lines
2.7 KiB
C++

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