2.1.7 Serial Bootloader

The Ethernet LaunchPad development kit enables the serial boot loader on the MSP432E401Y through the BSL header for connecting to an external BSL host interface, such as the BSL Rocket. The BSL header supports three communication protocols to the serial boot loader: SPI, UART, and I²C. To use the serial bootloader, a shrouded 100mil header (such as the AWHW-10G-0202-T from Assman WSW) should be soldered into the top side of the PCB, paying careful attention to make sure pin 1 of the connector lines up to pin one of the PCB (denoted by a square pad).

Because several of the pins for different communication protocols are shared on the header, the Ethernet LaunchPad development kit enables support for all three protocols by using 0-Ω resistor bridges for each of the signals. See Figure 4 for the location of the header and resistors on the PCB. To connect a specific protocol, populate the designated resistors with 0-Ω resistors and remove the resistors for the others protocols (see Table 6). When using I²C, populate R13 and R14 with the pullup resistors if no I²C pullups are on the external host. Typically the I²C pullup resistors should be 3.3 kΩ.

Figure 4. BSL Header and Resistors