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Moved the common "read/write register A and B together as a 16-bit 

value" functionality into a read function and a write function. Also
added ability to set pull-ups.
This commit is contained in:
Doug Brown 2011-11-26 22:17:17 -08:00
parent 34438a898e
commit 4c51019e30
2 changed files with 35 additions and 38 deletions
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72
mcp23s17.c
View File

@ -48,6 +48,10 @@ static bool MCP23S17_Inited = false;
#define MCP23S17_OLATA 0x14
#define MCP23S17_OLATB 0x15
// Private functions
void MCP23S17_WriteBothRegs(uint8_t addrA, uint16_t value);
uint16_t MCP23S17_ReadBothRegs(uint8_t addrA);
void MCP23S17_Init()
{
// If it has already been initialized, no need to do it again.
@ -91,37 +95,29 @@ void MCP23S17_Init()
void MCP23S17_SetDDR(uint16_t ddr)
{
ASSERT_CS();
// Just a temporary variable so we read
// the returned byte from the SPI transfer
volatile uint8_t tmp;
// Start off the communication by telling the MCP23S17 that we are writing to a register
SPDR = MCP23S17_CONTROL_WRITE(0);
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// Tell it which register we're writing to (IODIRA)
SPDR = MCP23S17_IODIRA;
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// Write the first byte of DDR
SPDR = (uint8_t)(ddr & 0xFF);
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// It should auto-increment to IODIRB now
SPDR = (uint8_t)((ddr >> 8) & 0xFF);
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
DEASSERT_CS();
MCP23S17_WriteBothRegs(MCP23S17_IODIRA, ddr);
}
void MCP23S17_SetPins(uint16_t data)
{
MCP23S17_WriteBothRegs(MCP23S17_GPIOA, data);
}
uint16_t MCP23S17_ReadPins(void)
{
return MCP23S17_ReadBothRegs(MCP23S17_GPIOA);
}
void MCP23S17_SetPullups(uint16_t pullups)
{
MCP23S17_WriteBothRegs(MCP23S17_GPPUA, pullups);
}
void MCP23S17_WriteBothRegs(uint8_t addrA, uint16_t value)
{
// addrA should contain the address of the "A" register.
// the chip should also be in "same bank" mode.
ASSERT_CS();
// Just a temporary variable so we read
@ -133,25 +129,25 @@ void MCP23S17_SetPins(uint16_t data)
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// Tell it which register we're writing to (GPIOA)
SPDR = MCP23S17_GPIOA;
// Tell it the first register we're writing to (the "A" register)
SPDR = addrA;
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// Write the first byte of GPIO
SPDR = (uint8_t)(data & 0xFF);
// Write the first byte of the register
SPDR = (uint8_t)(value & 0xFF);
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// It should auto-increment to GPIOB now
SPDR = (uint8_t)((data >> 8) & 0xFF);
// It should auto-increment to the "B" register, now write that
SPDR = (uint8_t)((value >> 8) & 0xFF);
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
DEASSERT_CS();
}
uint16_t MCP23S17_ReadPins(void)
uint16_t MCP23S17_ReadBothRegs(uint8_t addrA)
{
uint16_t returnVal;
@ -166,17 +162,17 @@ uint16_t MCP23S17_ReadPins(void)
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// Tell it which register we're reading from (GPIOA)
SPDR = MCP23S17_GPIOA;
// Tell it which register we're reading from (the "A" register)
SPDR = addrA;
while ((SPSR & (1 << SPIF)) == 0);
tmp = SPDR;
// Read the first byte of GPIOA
// Read the first byte of the register
SPDR = 0;
while ((SPSR & (1 << SPIF)) == 0);
returnVal = SPDR;
// It should auto-increment to IODIRB now
// It should auto-increment to the "B" register, now read that
SPDR = 0;
while ((SPSR & (1 << SPIF)) == 0);
returnVal |= (((uint16_t)SPDR) << 8);

1
mcp23s17.h
View File

@ -14,5 +14,6 @@ void MCP23S17_Init();
void MCP23S17_SetDDR(uint16_t ddr);
void MCP23S17_SetPins(uint16_t data);
uint16_t MCP23S17_ReadPins(void);
void MCP23S17_SetPullups(uint16_t pullups);
#endif /* MCP23S17_H_ */