Differences

This shows you the differences between two versions of the page.

--- microcontrollers:common_communication_types [2024/10/30 19:07] – ibchadmin
+++ microcontrollers:common_communication_types [2024/10/30 19:21] (current) – ibchadmin
@@ Line 74: / Line 74: @@
 ===== I2C (Inter-Integrated Circuit) =====
+The I2C lives on **UCBO** on a MSP430 board.
+{{ :microcontrollers:i2c.png?direct&400 |}}
+  * SDA: Data (default pin 1.6)
+  * SCL: Clock (default pin 1.7)
+Pull Low to send information.
+{{ :microcontrollers:i2c2.png?direct&400 |}}
+==== I2C Specifications ====
+  * Speed: 100 kbits/second - 3.4 Mbits/second
+  * Power: Bus draws power when SDA/SCL pulled low
+  * Vcc = 3.3V, Pullups = 4.7kΩ ∴ 0.7mA*2 = 1.4mA
+  * Larger resistors → Lower current draw
+  * Distance: I2C is limited by distance and the capacitance between SDA & SCL
+  * Designed for simple communication over a short distance
+==== Arbitration ====
+Using clock stretching, the bus can be easily arbitrated: this stalls the bus by holding SCL low.  This can be used to allow multiple nodes to be aware of when the bus is in use, or allow a device to stall the bus if more time is needed to handle data.
+==== Setup ====
+{{ :microcontrollers:i2c3.png?direct&400 |}}
+  * UCSWRST: Put USCI_B in reset state
+  * UCMODE_3: I2C Mode
+  * UCMST: Master Mode
+  * UCSYNC: Syncronous mode
+  * UCB0BRW: Baud rate SMCLK / 0x<UCB0BRW>
+==== Sending data ====
+{{ :microcontrollers:i2c4.png?direct&400 |}}
+==== Reading data ====
+{{ :microcontrollers:i2c5.png?direct&400 |}}
+{{ :microcontrollers:i2c6.png?direct&400 |}}
+===== References and Further Reading =====
+  * http://www.argenox.com/library/msp430/
+  * http://www.simplyembedded.org/tutorials/
+  * Msp430FR5994 User’s guide http://www.ti.com/lit/ug/slau367o/slau367o.pdf
+  * Evaluation of Power Efficiency for Digital Serial Interfaces of Microcontrollers  https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6208716