SWCU194 March 2023 CC1314R10 , CC1354P10 , CC1354R10 , CC2674P10 , CC2674R10
The bootloader supports the UART0 and SPI0 ports, which are available on the CC13x4x10 and CC26x4x10 device platform. The SPI0 port has the advantage of supporting higher and more flexible data rates, but it also requires more connections to the CC13x4x10 and CC26x4x10 device platform. The UART0 has the disadvantage of having slightly lower and possibly less flexible rates. However, the UART0 requires fewer pins and can be easily implemented with any standard UART connection.
Table 10-2 specifies which serial interface signals are configured to specific DIOs. These pins are fixed and cannot be reconfigured.
Signal | CC26x4x10 | CC1314R10 | CC1354x10 |
---|---|---|---|
UART0 RX | 12 | 2 | 12 |
UART0 TX | 13 | 3 | 13 |
SPI0_MISO | 8 | 8 | 8 |
SPI0_MOSI | 9 | 9 | 9 |
SPI0_CLK | 10 | 10 | 10 |
SPI0_CS | 11 | 11 | 11 |
The bootloader initially configures only the input pins on the two serial interfaces. By default, all I/O pins have their input buffers disabled, so the bootloader configures the required pins to be input pins so that the bootloader interface is not accessible from the host before this point in time. For this initial configuration of input pins, the firmware configures the IOC to route the input signals listed in Table 10-2 to their corresponding peripheral signals.
The bootloader selects the interface that is the first to be accessed by the external device. Once selected, the output pin for the selected interface (TX for UART0 or MOSI for SPI0) is configured and the other interface is disabled. To switch to the other interface, the CC13x4x10 and CC26x4x10 device platform must be reset. The delayed configuration of the TX pin imposes special consideration on the SPI0 host device regarding the transfer of the first byte of the first packet (see Section 10.2.2.2).