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Code Issues Releases Activity

Change Wire clock behavior (400 KHz default, override in constructor)

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This commit is contained in:
Phillip Burgess
2018-11-17 10:00:19 -08:00
parent 8504e3fd4b
commit 1973f0001f
3 changed files with 25 additions and 24 deletions
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Adafruit_SSD1306.cpp
+21 -21
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@@ -71,14 +71,6 @@
#define WIRE_WRITE wire->send ///< Wire write function in older Arduino lib
#endif
#if defined(__AVR__)
#define WIRECLK 400000L ///< AVR: use 400 KHz I2C clock
#elif defined(ESP32)
#define WIRECLK 800000L ///< ESP32: use 800 KHz I2C clock
#else
#define WIRECLK 1000000L ///< All others: use 1 MHz I2C clock
#endif
#ifdef HAVE_PORTREG
#define SSD1306_SELECT *csPort &= ~csPinMask; ///< Device select
#define SSD1306_DESELECT *csPort |= csPinMask; ///< Device deselect
@@ -92,7 +84,7 @@
#endif
#if (ARDUINO >= 157) && !defined(ARDUINO_STM32_FEATHER)
#define SETWIRECLOCK wire->setClock(WIRECLK) ///< Set before I2C transfer
#define SETWIRECLOCK wire->setClock(wireClk) ///< Set before I2C transfer
#define RESWIRECLOCK wire->setClock(restoreClk) ///< Restore after I2C xfer
#else // setClock() is not present in older Arduino Wire lib (or WICED)
#define SETWIRECLOCK ///< Dummy stand-in define
@@ -151,23 +143,31 @@
Reset pin (using Arduino pin numbering), or -1 if not used
(some displays might be wired to share the microcontroller's
reset pin).
@param res
Restore-to speed for Wire transmissions following library calls.
The library uses a faster-than-default Wire clock for quicker
screen updates, but this might not always be compatible with
other devices connected to the I2C bus. Arduino default Wire
speed (and the default value used here if not specified) is
100000 (100 KHz), but if your application knows it can reliably
use a higher data rate for other devices, that rate can be
specified here. (Ignored if using pre-1.5.7 Arduino software.)
@param clkDuring
Speed (in Hz) for Wire transmissions in SSD1306 library calls.
Defaults to 400000 (400 KHz), a known 'safe' value for most
microcontrollers, and meets the SSD1306 datasheet spec.
Some systems can operate I2C faster (800 KHz for ESP32, 1 MHz
for many other 32-bit MCUs), and some (perhaps not all)
SSD1306's can work with this -- so it's optionally be specified
here and is not a default behavior. (Ignored if using pre-1.5.7
Arduino software, which operates I2C at a fixed 100 KHz.)
@param clkAfter
Speed (in Hz) for Wire transmissions following SSD1306 library
calls. Defaults to 100000 (100 KHz), the default Arduino Wire
speed. This is done rather than leaving it at the 'during' speed
because other devices on the I2C bus might not be compatible
with the faster rate. (Ignored if using pre-1.5.7 Arduino
software, which operates I2C at a fixed 100 KHz.)
@return Adafruit_SSD1306 object.
@note Call the object's begin() function before use -- buffer
allocation is performed there!
*/
Adafruit_SSD1306::Adafruit_SSD1306(uint8_t w, uint8_t h, TwoWire *twi,
int8_t rst_pin, uint32_t res) : Adafruit_GFX(w, h),
spi(NULL), wire(twi ? twi : &Wire), buffer(NULL), mosiPin(-1), clkPin(-1),
dcPin(-1), csPin(-1), rstPin(rst_pin), restoreClk(res) {
int8_t rst_pin, uint32_t clkDuring, uint32_t clkAfter) :
Adafruit_GFX(w, h), spi(NULL), wire(twi ? twi : &Wire), buffer(NULL),
mosiPin(-1), clkPin(-1), dcPin(-1), csPin(-1), rstPin(rst_pin),
wireClk(clkDuring), restoreClk(clkAfter) {
}
/*!