Some code to test 23K256 SPI SRAM on Nanode

SRAM_test.c

// SPI SRAM/EPROM  Speed Test

// Written by Ken Boak for Nanode SRAM tests  May 22 2011

// Simple test of the 23K256 32Kx8 SRAM on the Nanode 5 board
// Remember to write 0 to the status register to put it into byte mode (not page or streaming mode)
// Before each write take the select line low and then high again after each write!
// Writes 32K bytes in about 2.68 seconds - with digital write 12,226 per second 

// These tests are for random access mode
// For sreaming mode the whole 32K may be read in 116mS !!
// See Arduino Playground here for more details of streaming mode
// and a library which supports the 23K256 SPI SRAM
// http://www.arduino.cc/playground/Main/SpiRAM



// With SLAVESELECT being written to direct to port pin  32kbytes write is 2.4 seconds
// and read spi is reduced from 15.04uS to 10.8uS

//  With address incrementation this comes to 13.28uS or 26.6 uS to read a 16 bit integer - say 27uS 

// These figures can be improved for paged or streaming mode for multiple bytes

// Now tested with direct write

/*

Pin 9 = Port B1  Slave Select
Pin 10 = Port B2  
Pin 11 = Port B3  MOSI
Pin 12 = Port B4 MISO
Pin 13 = SCK

DDRB = DDRB | B11101111;  // Sets pins 12 as input, 8-15 output


// DDRD = DDRD | B11111100;  // Sets pins 2 to 7 as outputs
        
        pinMode(6,OUTPUT);
        
        PORTD |= (1<<PD7) ;        //  PORTD. 7 = 1     
//        dlihb()        ;        //  dly halfbit through instructions     
        PORTD &= ~(1<<PD7) ;        //  PORTD. 7 = 0 
//        dlihb()        ;        //  dly halfbit through instructions


*/

#include <avr/io.h>    // include the Port pin definitions

#define DATAOUT 11//MOSI
#define DATAIN  12//MISO 
#define SPICLOCK  13//sck
#define SLAVESELECT 9//ss
#define LED 6 // LED on pin 6 - when pulled LOW!

//opcodes
#define WREN  6
#define WRDI  4
#define RDSR  5
#define WRSR  1
#define READ  3
#define WRITE 2


#define  PD7     PORTD7     // digital 7
#define  PB1     PORTB1    // digital 9

byte eeprom_output_data;
byte eeprom_input_data=0;
byte clr;
int address=0;
long start_time;
long stop_time;
long duration;

//data buffer
char buffer [128];

void fill_buffer()
{
  for (int I=0;I<128;I++)
  {
    buffer[I]=I;
  }
}

char spi_transfer(volatile char data)
{
  SPDR = data;                    // Start the transmission
  while (!(SPSR & (1<<SPIF)))     // Wait the end of the transmission
  {
  };
  return SPDR;                    // return the received byte
}

void setup()
{
  Serial.begin(9600);
  
  DDRB = DDRB | B11101111;  // Sets pins 12 as input, 8-15 output

  pinMode(DATAOUT, OUTPUT);
  pinMode(DATAIN, INPUT);
  pinMode(SPICLOCK,OUTPUT);
  pinMode(LED, OUTPUT);
  digitalWrite(LED,HIGH); //LED Off
  pinMode(SLAVESELECT,OUTPUT);
  digitalWrite(SLAVESELECT,HIGH); //disable device
  // SPCR = 01010000
  //interrupt disabled,spi enabled,msb 1st,master,clk low when idle,
  //sample on leading edge of clk,system clock/4 rate (fastest)
  SPCR = (1<<SPE)|(1<<MSTR);
  clr=SPSR;
  clr=SPDR;
  delay(10);
  //fill buffer with data
  fill_buffer();  //fill eeprom w/ buffer
  
  
  
  digitalWrite(SLAVESELECT,LOW);
  spi_transfer(WRSR); //write to status register
  spi_transfer(0);  // byte mode
  digitalWrite(SLAVESELECT,HIGH);

  digitalWrite(LED,LOW);
  start_time = millis();
  for (int I=0;I<32767;I++)   // Write the 128 byte buffer to the RAM
  {
  // digitalWrite(SLAVESELECT,LOW);
  PORTB &= ~(1<<PB1) ;        //  SLAVESELECT = 0 
  
  spi_transfer(WRITE); //write instruction
  address=I;
  spi_transfer((char)(address>>8));   //send MSByte address first
  spi_transfer((char)(address));      //send LSByte address
//  spi_transfer(buffer[I]); //write data byte
  spi_transfer(I/4);
  
   PORTB |= (1<<PB1) ;        //  SLAVESELECT =  1    
//  digitalWrite(SLAVESELECT,HIGH); //release chip 
  }
   stop_time = millis();
   duration = stop_time-start_time;
   delay(2000);
    Serial.println(start_time);
     Serial.println(stop_time);
   Serial.println(duration);
   
  digitalWrite(LED,HIGH);
  
  //wait for eeprom to finish writing
  delay(3000);
  Serial.print('h',BYTE);
  Serial.print('i',BYTE);
  Serial.print('\n',BYTE);//debug
  delay(1000);
}

byte read_eeprom(int EEPROM_address)
{
  //READ EEPROM
  int data;
//  digitalWrite(SLAVESELECT,LOW);
  PORTB &= ~(1<<PB1) ;        //  SLAVESELECT = 0 
  spi_transfer(READ); //transmit read opcode
  spi_transfer((char)(EEPROM_address>>8));   //send MSByte address first
  spi_transfer((char)(EEPROM_address));      //send LSByte address
  data = spi_transfer(0xFF); //get data byte
  PORTB |= (1<<PB1) ;        //  SLAVESELECT =  1  
//  digitalWrite(SLAVESELECT,HIGH); //release chip, signal end transfer
  return data;
}

void loop()
{
  eeprom_output_data = read_eeprom(address);
//  Serial.print(eeprom_output_data,DEC);
//  Serial.print("'");
//  Serial.print('\n',BYTE);
  address++;
  if (address == 32767)
    address = 0;
//  delay(500); //pause for readability
}