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Add 74LS595 code to the HardwareVerify sketch

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This commit is contained in:
Tom Nisbet 2020-10-11 23:16:15 -04:00
parent e45f1e3377
commit 6d9a958907
2 changed files with 36 additions and 40 deletions
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74
HardwareVerify/PromAddressDriver.cpp
View File

@ -1,9 +1,28 @@
// This controls the shift register that generates the address lines for A0..A15 for most
// chip families.
//
// Note that this uses direct port control instead of digitalWrite calls so that the code
// can run fast enough to meet the tBLC requirements for SDP and block writes. This
// sacrifices portability and readability for speed.
//
// This code will only work on Arduino Uno and Nano hardware. The ports for other
// Arduinos map to different IO pins.
#include "PromAddressDriver.h"
#define ADDR_CLK_HI A3
#define ADDR_CLK_LO A4
#define ADDR_DATA A5
// Define masks for the address clk and data lines on PC3..PC5 for direct port control.
#define ADDR_CLK_HI_MASK 0x08
#define ADDR_CLK_LO_MASK 0x10
#define ADDR_DATA_MASK 0x20
// When using the 74LS595 shift registers, the RCLK lines of both shift registers can be
// connected to D13 (PB5).
#define RCLK_595_MASK 0x20
void PromAddressDriver::begin()
{
@ -14,7 +33,7 @@ void PromAddressDriver::begin()
digitalWrite(ADDR_DATA, LOW);
digitalWrite(ADDR_CLK_LO, LOW);
digitalWrite(ADDR_CLK_HI, LOW);
DDRB |= RCLK_595_MASK; // Set D13 as output
// 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,
@ -33,50 +52,22 @@ void PromAddressDriver::setAddress(word address)
if (hi != lastHi)
{
setAddressRegisterDirect(ADDR_CLK_HI, hi);
setAddressRegister(ADDR_CLK_HI, hi);
lastHi = hi;
}
setAddressRegisterDirect(ADDR_CLK_LO, lo);
setAddressRegister(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;
if (clkPin == ADDR_CLK_HI)
mask = ADDR_CLK_HI_MASK;
else if (clkPin == ADDR_CLK_LO)
mask = ADDR_CLK_LO_MASK;
// Make sure the clock is low to start.
PORTC &= ~mask;
@ -87,11 +78,11 @@ void PromAddressDriver::setAddressRegisterDirect(uint8_t clkPin, byte addr)
// Set the data bit
if (addr & 0x80)
{
PORTC |= 0x20;
PORTC |= ADDR_DATA_MASK;
}
else
{
PORTC &= 0xdf;
PORTC &= ~ADDR_DATA_MASK;
}
// Toggle the clock high then low
@ -100,5 +91,12 @@ void PromAddressDriver::setAddressRegisterDirect(uint8_t clkPin, byte addr)
PORTC &= ~mask;
addr <<= 1;
}
}
// Toggle the output latch for 74LS595 hardware. For the default TommyPROM hardware
// this just harmlessly writes to the D13 line that isn't connected to anything.
PORTB &= ~RCLK_595_MASK;
delayMicroseconds(1);
PORTB |= RCLK_595_MASK;
delayMicroseconds(1);
PORTB &= ~RCLK_595_MASK;
}

2
HardwareVerify/PromAddressDriver.h
View File

@ -10,9 +10,7 @@ class PromAddressDriver {
private:
static void setAddressRegister(uint8_t clkPin, byte addr);
static void setAddressRegisterDirect(uint8_t clkPin, byte addr);
};
#endif // #define INCLUDE_PROM_ADDRESS_DRIVER_H