Implemented vm memory using external 23LCV512 chip.

Todo: implement extended registers

arduino/memory.cpp

@@ -0,0 +1,127 @@
+/*
+Copyright 2018 Sam Stevens
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+ */
+
+#include "memory.h"
+
+Memory::Memory(uint32_t clock, uint8_t bitOrder, uint8_t dataMode, uint8_t csPin) {
+  //Set cs pin high
+  this->csPin = csPin;
+  pinMode(csPin, OUTPUT);
+  digitalWrite(csPin, HIGH);
+  //Default to 64k ram
+  this->memSize = 0xFFFF;
+  //Store spi setting
+  this->setting = SPISettings(clock, bitOrder, dataMode);
+}
+
+void Memory::start() {
+  digitalWrite(this->csPin, LOW);
+  SPI.beginTransaction(this->setting);
+}
+void Memory::end() {
+  SPI.endTransaction();
+  digitalWrite(this->csPin, HIGH);
+}
+
+bool Memory::init() {
+  //Set mode to sequential access (should be default mode)
+  this->start();
+  SPI.transfer(INSTR_WRMR);
+  SPI.transfer(MODE_SEQ);
+  this->end();
+
+  //Verify that it was set
+  this->start();
+  SPI.transfer(INSTR_RDMR);
+  uint8_t mode = SPI.transfer(0);
+  this->end();
+  
+  return mode == MODE_SEQ;
+}
+
+uint16_t Memory::getSize() {
+  return this->memSize;
+}
+
+void Memory::setSize(uint16_t memSize) {
+  this->memSize = memSize;
+}
+
+uint8_t Memory::read(uint16_t addr) {
+  this->start();
+  SPI.transfer(INSTR_READ);
+  SPI.transfer16(addr);
+  uint8_t data = SPI.transfer(0);
+  this->end();
+  return data;
+}
+
+void Memory::write(uint16_t addr, uint8_t data) {
+  this->start();
+  SPI.transfer(INSTR_WRITE);
+  SPI.transfer16(addr);
+  SPI.transfer(data);
+  this->end();
+}
+
+void Memory::writeRange(uint8_t data, uint16_t from, uint16_t to) {
+  if (from > to) {
+    return;
+  }
+  this->start();
+  SPI.transfer(INSTR_WRITE);
+  SPI.transfer16(from);
+  for(uint32_t i = from; i < to; i++) {
+    SPI.transfer(data);
+  }
+  this->end();
+}
+
+bool Memory::verifyRange(uint8_t data, uint16_t from, uint16_t to) {
+  if (from > to) {
+    return false;
+  }
+  this->start();
+  SPI.transfer(INSTR_READ);
+  SPI.transfer16(from);
+  bool ok = true;
+  for(uint32_t i = from; i < to; i++) {
+    if (SPI.transfer(0) != data) {
+      ok = false;
+      break;
+    }
+  }
+  this->end();
+  return ok;
+}
+
+bool Memory::test() {
+  //write 0x55 (01010101)
+  this->writeRange(0x55, 0, this->memSize);
+  //verify
+  if (!this->verifyRange(0x55, 0, this->memSize)) {
+    return false;
+  }
+  
+  //write zeros
+  this->writeRange(0, 0, this->memSize);
+  //verify zeros
+  if (!this->verifyRange(0, 0, this->memSize)) {
+    return false;
+  }
+  return true;
+}
+