MCP23008.cpp

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#include "MCP23008.hh"

bool
MCP23008::begin()
{
  uint8_t reg[REG_MAX];
  uint8_t config;
  int res;

  memset(reg, 0, sizeof(reg));
  reg[IODIR] = 0xff;
  twi.acquire(this);
  res = twi.write((uint8_t) IODIR, reg, sizeof(reg));
  twi.release();
  if (res != sizeof(reg) + 1) return (false);

  config = _BV(SEQOP);
  twi.acquire(this);
  res = twi.write((uint8_t) IOCON, &config, sizeof(config));
  twi.release();
  m_reg = IOCON;

  return (res == sizeof(config) + 1);
}

bool
MCP23008::data_direction(uint8_t iodir)
{
  m_iodir = iodir;
  twi.acquire(this);
  int res = twi.write((uint8_t) IODIR, &m_iodir, sizeof(m_iodir));
  twi.release();
  m_reg = IODIR;
  return (res == sizeof(m_iodir) + 1);
}

bool
MCP23008::pullup(uint8_t gppu)
{
  m_gppu = gppu;
  twi.acquire(this);
  int res = twi.write((uint8_t) GPPU, &m_gppu, sizeof(m_gppu));
  twi.release();
  m_reg = GPPU;
  return (res == sizeof(m_gppu) + 1);
}

bool
MCP23008::interrupt_pin(uint8_t pin, InterruptMode mode)
{
  uint8_t mask = _BV(pin & PIN_MASK);
  int res;
  switch (mode) {
  case DISABLE:
    m_gpinten &= ~mask;
    m_defval &= ~mask;
    m_intcon &= ~mask;
    break;
  case ON_CHANGE:
    m_gpinten |= mask;
    m_defval &= ~mask;
    m_intcon &= ~mask;
    break;
  case ON_FALLING:
    m_gpinten |= mask;
    m_defval |= mask;
    m_intcon |= mask;
    break;
  case ON_RISING:
    m_gpinten |= mask;
    m_defval &= ~mask;
    m_intcon |= mask;
    break;
  }
  twi.acquire(this);
  res = twi.write((uint8_t) GPINTEN, &m_gpinten, sizeof(m_gpinten));
  if (res != sizeof(m_gpinten) + 1) goto error;
  res = twi.write((uint8_t) DEFVAL, &m_defval, sizeof(m_defval));
  if (res != sizeof(m_defval) + 1) goto error;
  res = twi.write((uint8_t) INTCON, &m_intcon, sizeof(m_intcon));
  if (res != sizeof(m_intcon) + 1) goto error;
  twi.release();
  return (true);
 error:
  twi.release();
  return (false);
}

uint8_t
MCP23008::read()
{
  uint8_t res;
  twi.acquire(this);
  if (m_reg != GPIO) {
    twi.write((uint8_t) GPIO);
    m_reg = GPIO;
  }
  twi.read(&res, sizeof(res));
  twi.release();
  return (res);
}

bool
MCP23008::read(void* buf, size_t size)
{
  if (UNLIKELY(size == 0)) return (true);
  int res = 0;
  twi.acquire(this);
  if (m_reg != GPIO) {
    twi.write((uint8_t) GPIO);
    m_reg = GPIO;
  }
  res = twi.read(buf, size);
  twi.release();
  return (res == (int) size);
}

bool
MCP23008::write(uint8_t value)
{
  m_olat = value;
  twi.acquire(this);
  int res = twi.write((uint8_t) OLAT, &m_olat, sizeof(m_olat));
  twi.release();
  m_reg = OLAT;
  return (res == sizeof(m_olat) + 1);
}

bool
MCP23008::write(void* buf, size_t size)
{
  if (UNLIKELY(size == 0)) return (true);
  twi.acquire(this);
  int res = twi.write((uint8_t) OLAT, buf, size);
  twi.release();
  uint8_t* bp = (uint8_t*) buf;
  size_t ix = size - 1;
  m_olat = bp[ix];
  m_reg = OLAT;
  return (res == (int) size + 1);
}