forked from Apple-2-HW/TommyPROM
25996ca934
Classes now in separate files PromDevice classes used to allow for a choice of hardware support ErasedCheck command Support for Intel 8755 EPROM
116 lines
2.9 KiB
C++
116 lines
2.9 KiB
C++
#include "Configure.h"
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#if defined(PROM_IS_8755)
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#define CE1 A0
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#define CE2 A1
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#define RD A2
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#define AD8 A5
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#define AD9 A4
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#define AD10 A3
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#define ALE 12
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#define VDDCTL 11
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PromDevice8755::PromDevice8755(unsigned long size)
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: PromDevice(size, 0, 0, false)
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{
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}
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void PromDevice8755::begin()
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{
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// Define the data bus as input initially so that it does not put out a
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// signal that could collide with output on the data pins of the EEPROM.
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setDataBusMode(INPUT);
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// Define the EEPROM control pins as output, making sure they are all
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// in the disabled state.
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digitalWrite(RD, HIGH);
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pinMode(RD, OUTPUT);
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digitalWrite(VDDCTL, LOW);
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pinMode(VDDCTL, OUTPUT);
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digitalWrite(CE1, LOW);
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pinMode(CE1, OUTPUT);
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digitalWrite(CE2, LOW);
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pinMode(CE2, OUTPUT);
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digitalWrite(ALE, LOW);
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pinMode(ALE, OUTPUT);
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// The address control pins are always outputs.
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pinMode(AD8, OUTPUT);
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pinMode(AD9, OUTPUT);
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pinMode(AD10, OUTPUT);
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digitalWrite(AD8, LOW);
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digitalWrite(AD9, LOW);
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digitalWrite(AD10, LOW);
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}
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// BEGIN PRIVATE METHODS
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//
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// Set an 11 bit address using the 8 address/data bus lines and three more dedicated
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// address lines. The read and burn code will take care of the ALE line
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void PromDevice8755::setAddress(word address)
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{
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writeDataBus(byte(address & 0xff));
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digitalWrite(AD8, address & 0x100 ? HIGH : LOW);
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digitalWrite(AD9, address & 0x200 ? HIGH : LOW);
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digitalWrite(AD10, address & 0x400 ? HIGH : LOW);
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}
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// Read a byte from a given address
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byte PromDevice8755::readByte(word address)
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{
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byte data = 0;
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digitalWrite(RD, HIGH);
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digitalWrite(CE1, LOW);
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// Put the address on the bus and latch it with ALE
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digitalWrite(CE2, HIGH);
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setDataBusMode(OUTPUT);
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setAddress(address);
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digitalWrite(ALE, HIGH);
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digitalWrite(ALE, LOW);
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// Read a byte
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setDataBusMode(INPUT);
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setAddress(0xff);
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digitalWrite(RD, LOW);
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delayMicroseconds(1);
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data = readDataBus();
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digitalWrite(RD, HIGH);
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digitalWrite(CE2, LOW);
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return data;
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}
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// Burn a byte to the chip and verify that it was written.
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bool PromDevice8755::burnByte(byte value, word address)
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{
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// Latch the address and the CE lines
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digitalWrite(ALE, HIGH);
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digitalWrite(CE1, LOW);
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digitalWrite(CE2, HIGH);
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setAddress(address);
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digitalWrite(ALE, LOW);
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// Burn the byte value by setting CE1 high and then setting VDD to +25V for 50ms.
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setDataBusMode(OUTPUT);
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writeDataBus(value);
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digitalWrite(CE1, HIGH);
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digitalWrite(VDDCTL, HIGH);
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delay(50);
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digitalWrite(VDDCTL, LOW);
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digitalWrite(CE1, LOW);
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// Read back the value and return success if it matches
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return readByte(address) == value;
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}
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#endif // #if defined(PROM_IS_8755)
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