SLAU573C November   2015  – October 2019

 

  1.   MSP-BSL Bootloader (BSL) Programmer for MSP430™ and SimpleLink™ MSP432™ Microcontrollers
    1.     Trademarks
    2. 1 Introduction
      1. 1.1 Additional Online Information
    3. 2 Functionality and Supported Protocols
      1. 2.1 BSL Entry Sequence
      2. 2.2 UART Communication
      3. 2.3 I2C Communication
      4. 2.4 SPI Communication
    4. 3 Firmware Update
    5. 4 Hardware
      1. 4.1 Schematic
      2. 4.2 BSL Connector and Available Pins
      3. 4.3 Target Power Supply
      4. 4.4 Pullups for I2C Operation
    6. 5 Firmware Revision History
  2.   Revision History

2.3 I2C Communication

Similar to the UART mode, the MSP-BSL supports the I2C protocol, starting with firmware version 2.1. All data sent to the virtual COM port is output on the SDA and SCL pins (see Section 4.2). Data received from I2C is forwarded to the PC. The MSP-BSL acts as a transparent USB-to-I2C bridge, except that it returns an error code (055h) to the PC if the I2C communication fails. The MSP-BSL has a state machine that emulates this transparent behavior.

The MSP-BSL operates as an I2C master and uses 7-bit addressing mode. The slave address for the MSP430 or MSP432P4xx target is 048h, and the slave address for the MSP432E4 target is 042h.

To start I2C BSL communication, perform the following steps, depending on the device family.

For the MSP430 family:

  1. The host triggers the MSP-BSL Rocket with 100001 or 400001 bit rate.
  2. The slave address generated by MSP-BSL Rocket is 0x48.
  3. For custom I2C address only : The host triggers the MSP-BSL Rocket with (100000 + slaveAddress) or (400000 + slaveAddress).
  4. The host starts the programming with 100000 or 400000 standard bit rate.

For the MSP432P4xx family:

  1. The slave address generated by MSP-BSL Rocket is 0x48.
  2. For custom I2C address only : The host triggers the MSP-BSL Rocket with (100000 + slaveAddress) or (400000 + slaveAddress).
  3. The host starts the programming with 100000 or 400000 standard bit rate.

For the MSP432E4 family:

  1. The host triggers the MSP-BSL Rocket with 100008 or 400008 bit rate.
  2. The slave address generated by MSP-BSL Rocket is 0x48.
  3. For custom I2C address only : The host triggers the MSP-BSL Rocket with (100000 + slaveAddress) or (400000 + slaveAddress).
  4. The host starts the programming with 100000 or 400000 standard bit rate.

The MSP-BSL supports I2C Standard Mode (Sm) with a maximum transfer rate of 100 kbps and I2C Fast Mode (Fm) with a maximum transfer rate of 400 kbps. Both of these modes are selected by changing the bit rate of the serial connection from the PC to the MSP-BSL.

NOTE

I2C communication requires pullup resistors on the SDA and SCL lines. The pullup resistors can be soldered on the MSP-BSL PCB (see Section 4.4), or they can be included in the target application design; for example, by adding jumpers to the I2C pullups on the MSP430 or MSP432 target socket board.

TI recommends pullup resistors of 2 to 4 kΩ.