AceWire
0.4.0
Unified interface for selecting different I2C implementations on Arduino platforms
|
A version of SimpleWireInterface that uses one of the <digitalWriteFast.h> libraries. More...
#include <SimpleWireFastInterface.h>
Public Member Functions | |
SimpleWireFastInterface ()=default | |
Constructor. | |
void | begin () const |
Initialize the clock and data pins. More... | |
void | end () const |
Set clock and data pins to INPUT mode. | |
uint8_t | beginTransmission (uint8_t addr) const |
Send I2C START condition. More... | |
uint8_t | write (uint8_t data) const |
Send the data byte on the data bus, with MSB first as specified by I2C. More... | |
uint8_t | endTransmission (bool sendStop=true) const |
Send the I2C STOP condition. More... | |
uint8_t | requestFrom (uint8_t addr, uint8_t quantity, bool sendStop=true) const |
Prepare to read bytes by sending I2C START condition. More... | |
uint8_t | read () const |
Read byte. More... | |
SimpleWireFastInterface (const SimpleWireFastInterface &)=default | |
SimpleWireFastInterface & | operator= (const SimpleWireFastInterface &)=default |
A version of SimpleWireInterface that uses one of the <digitalWriteFast.h> libraries.
The biggest benefit of using digitalWriteFast is the reduction of flash memory size, 500-700 bytes on AVR.
The delayMicroseconds()
may not be accurate for small values on some processors (e.g. AVR) . The actual minimum value of T_DELAY_MICROS will depend on the capacitance and resistance on the DATA and CLOCK lines, and the accuracy of the delayMicroseconds()
function.
T_DATA_PIN | SDA pin |
T_CLOCK_PIN | SCL pin |
T_DELAY_MICROS | delay after each bit transition of SDA or SCL |
Definition at line 52 of file SimpleWireFastInterface.h.
|
inline |
Initialize the clock and data pins.
These are open-drain lines, with pull-up resistors. We must not drive them HIGH actively since that could damage the transitor at the other end of the line pulling LOW. Instead, we go into INPUT mode to let the line to HIGH through the pullup resistor, then go to OUTPUT mode only to pull down.
Definition at line 66 of file SimpleWireFastInterface.h.
|
inline |
Send I2C START condition.
addr | I2C address of slave device |
Definition at line 87 of file SimpleWireFastInterface.h.
|
inline |
Send the I2C STOP condition.
Definition at line 136 of file SimpleWireFastInterface.h.
|
inline |
Read byte.
After reading 8 bits, an ACK or NACK will be sent by the master to the slave. ACK means the slave will be asked to send more bytes so can hold control of the data line. NACK means no more bytes will be read from the slave and the slave should release the data line.
If requestFrom() was called with sendStop = true
, a STOP condition will be sent after reading the final byte.
If called when the number of remaining bytes is 0 (which should not happen if the calling program is correctly implemented), this method returns immediately with a 0xff.
Definition at line 185 of file SimpleWireFastInterface.h.
|
inline |
Prepare to read bytes by sending I2C START condition.
If sendStop
is true, then a STOP condition will be sent by read()
after the last byte.
Definition at line 154 of file SimpleWireFastInterface.h.
|
inline |
Send the data byte on the data bus, with MSB first as specified by I2C.
This loop generates slightly asymmetric logic signals because clockLow() lasts for 2*bitDelay(), but clockHigh() lasts for only 1*bitDelay(). This does not seem to cause any problems with the LED modules that I have tested.
Definition at line 110 of file SimpleWireFastInterface.h.