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→Utilisation du TCA9548A
En théorie, il est possible d'utiliser jusque 8 multiplexeurs sur un même bus (un pour chaque adresse entre 0x70 et 0x77). Cela permet de contrôler jusqu'à 64 fois la même adresse sans collision.
En théorie, il est possible d'utiliser jusque 8 multiplexeurs sur un même bus (un pour chaque adresse entre 0x70 et 0x77). Cela permet de contrôler jusqu'à 64 fois la même adresse sans collision.
[[Fichier:TCA9548A-pinout.png]]
=== Alimentation ===
* '''Vin''' : this is the power pin. Since the sensor chip uses 3-5 VDC. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V
* '''GND''' : common ground for power and logic
=== I2C Control-Side pins ===
* '''SCL''' : this is the I2C clock pin for the chip itself, connect to your microcontrollers I2C clock line.
* '''SDA''' : this is the I2C data pin for the chip itself, connect to your microcontrollers I2C data line.
* '''RST''' : this is the reset pin, for resetting the multiplexer chip. Pulled high by default, connect to ground to reset
* '''A0 A1 A2''' : these are the address selection pins for the multiplexer. By default the multiplexer is at address 0x70 and these three pins are pulled low. Connect them to Vin to set the address to 0x71 - 0x77. A0 à un poids de 1, A1 à un poids de 2, A2 à un poids de 4.
=== Broches I2C multiplexées ===
'''SDx''' et '''SCx''' : There are 8 sets of '''SDx''' and '''SCx''' pins, from '''SD0/SC0''' to '''SD7/SC7'''.
These are the multiplexed pins. Each one is a completely seperate I2C bus set.
So you have have 8 I2C devices with identical addresses, as long as they are on one I2C bus each.
These pins do not have any pullups installed, so if you are using a chip or breakout without i2c pullups be sure to add them! Nicely, you can have '''Vin''' be 3.3V and have these pins pulled up to 5V (that is, they are 5V compliant).
=== Utilisation avec Arduino ===
We suggest using this little helper to help you select the port (de 0 à 7).
<nowiki>#define TCAADDR 0x70
void tcaselect(uint8_t i) {
if (i > 7) return;
Wire.beginTransmission(TCAADDR);
Wire.write(1 << i);
Wire.endTransmission();
}</nowiki>
You can then call {{fname|tcaselect(0)}} à {{fname|tcaselect(7)}} to set up the multiplexer.
Un code d'exemple Arduino plus complet est disponible sur [https://learn.adafruit.com/adafruit-tca9548a-1-to-8-i2c-multiplexer-breakout/wiring-and-test cette page du tutoriel Adafruit].
{{I2C-Hacking-TRAILER}}
{{I2C-Hacking-TRAILER}}