/**
* Reads multiple bytes from a register.
*
* @param reg register to read from.
* @param count number of bytes to read.
* @param values target buffer.
* @return pointer to the input buffer + count.
*/
uint8_t * max3421e_readMultiple(uint8_t reg, uint8_t count, uint8_t * values)
{
// Pull slave-select high to initiate transfer.
MAX_SS(0);
// Send a command byte containing the register number.
SPDR = reg;
while (!(SPSR & (1 << SPIF))); //wait
// Read [count] bytes.
while (count--)
{
// Send empty byte while reading.
SPDR = 0;
while (!(SPSR & (1 << SPIF)));
*values = SPDR;
values++;
}
// Pull slave-select low to signal transfer complete.
MAX_SS(1);
// Return the byte array + count.
return (values);
}
/*
* Initialises the max3421e host shield. Initialises the SPI bus and sets the required pin directions.
* Must be called before powerOn.
*/
void max3421e_init()
{
spi_begin();
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
// Set MAX_INT and MAX_GPX pins to input mode.
DDRH &= ~(0x40 | 0x20);
// Set SPI !SS pint to output mode.
DDRB |= 0x10;
// Set RESET pin to output
DDRH |= 0x10;
#elif defined(__AVR_ATmega168__) || defined(__AVR_ATmega328P__)
// Set MAX_INT and MAX_GPX pins to input mode.
DDRB &= ~0x3;
// Set RESET pin to output
DDRD |= 0x80;
// Set SS pin to output
DDRB |= 0x4;
#endif
// Sparkfun botched their first attempt at cloning Oleg's max3421e shield and reversed the GPX and RESET pins.
// This hack is in place to make MicroBridge work with those shields. (see http://www.sparkfun.com/products/9628)
#ifdef SFHACK
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
// Set MAX_GPX pin to input mode.
DDRH &= ~0x10;
// Set RESET pin to output
DDRH |= 0x20;
#elif defined(__AVR_ATmega168__) || defined(__AVR_ATmega328P__)
// Set GPX pin to input
DDRD &= ~0x80;
// Set RESET pin to output
DDRB |= 0x1;
#endif
#endif
// Pull SPI !SS high
MAX_SS(1);
// Reset
MAX_RESET(1);
}
/**
* Writes a single register.
*
* @param reg register address.
* @param value value to write.
*/
void max3421e_write(uint8_t reg, uint8_t value)
{
// Pull slave select low to indicate start of transfer.
MAX_SS(0);
// Transfer command byte, 0x02 indicates write.
SPDR = (reg | 0x02);
while (!(SPSR & (1 << SPIF)));
// Transfer value byte.
SPDR = value;
while (!(SPSR & (1 << SPIF)));
// Pull slave select high to indicate end of transfer.
MAX_SS(1);
return;
}
/**
* Reads a single register.
*
* @param reg register address.
* @return result value.
*/
uint8_t max3421e_read(uint8_t reg)
{
// Pull slave-select high to initiate transfer.
MAX_SS(0);
// Send a command byte containing the register number.
SPDR = reg;
while (!(SPSR & (1 << SPIF)));
// Send an empty byte while reading.
SPDR = 0;
while (!(SPSR & (1 << SPIF)));
// Pull slave-select low to signal transfer complete.
MAX_SS(1);
// Return result byte.
return (SPDR);
}
/*
* Initialises the max3421e host shield. Initialises the SPI bus and sets the required pin directions.
* Must be called before powerOn.
*/
void max3421e_init()
{
SPI.begin();
#ifndef __AVR_ATmega2560__
pinMode(PIN_MAX_INT, INPUT);
pinMode(PIN_MAX_GPX, INPUT);
pinMode(PIN_MAX_SS, OUTPUT);
pinMode(PIN_MAX_RESET, OUTPUT);
#endif
#ifdef __AVR_ATmega2560__
pinMode(PIN_MAX_SS, OUTPUT);
DDRE &= ~ 0x40; // MAX_INT as input
DDRJ &= ~ 0x08; //MAX_GPX as input
DDRJ |= 0x04; //MAX_RESET as output
#endif
/*
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
// Set MAX_INT and MAX_GPX pins to input mode.
DDRH &= ~(0x40 | 0x20);
// Set SPI !SS pint to output mode.
DDRB |= 0x10;
// Set RESET pin to output
DDRH |= 0x10;
#elif defined(__AVR_ATmega168__) || defined(__AVR_ATmega328P__)
// Set MAX_INT and MAX_GPX pins to input mode.
DDRB &= ~0x3;
// Set RESET pin to output
DDRD |= 0x80;
// Set SS pin to output
DDRB |= 0x4;
#endif
*/
// Pull SPI !SS high
MAX_SS(1);
// Reset
MAX_RESET(1);
}
/**
* Writes multiple bytes to a register.
* @param reg register address.
* @param count number of bytes to write.
* @param vaues input values.
* @return a pointer to values, incremented by the number of bytes written (values + length).
*/
uint8_t * max3421e_writeMultiple(uint8_t reg, uint8_t count, uint8_t * values)
{
// Pull slave select low to indicate start of transfer.
MAX_SS(0);
// Transfer command byte, 0x02 indicates write.
SPDR = (reg | 0x02);
while (!(SPSR & (1 << SPIF)));
// Transfer values.
while (count--)
{
// Send next value byte.
SPDR = (*values);
while (!(SPSR & (1 << SPIF)));
values++;
}
// Pull slave select high to indicate end of transfer.
MAX_SS(1);
return (values);
}