SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The CC32xx implements a sense-on-power scheme. By using a few board-level pull resistors, the user can configure the CC32xx to power up in one of the three following modes:
Sense-on-power (SoP) values are sensed from the device pin during power up. This encoding determines the boot flow, as well as the default mapping for some of the pins (JTAG, SWD, UART0). Three SoP pins are used for this purpose. Before the device is taken out of reset, the SoP values are made available on a register and determine the device character while powering up. CC3235x Functional Configurations shows the pull configurations.
| BOOT MODE NAME | SOP[2] | SOP[1] | SOP[0] | SOP MODE | COMMENT |
|---|---|---|---|---|---|
| UARTLOAD | Pullup | Pulldown | Pulldown | LDfrUART | Factory, lab flash, and SRAM loads through the UART. The device waits indefinitely for the UART to load code. The SOP bits then must be toggled to configure the device in functional mode. Also puts JTAG in 4-wire mode. |
| FUNCTIONAL_2WJ | Pulldown | Pulldown | Pullup | Fn2WJ | Functional development mode. In this mode, 2-pin SWD is available to the developer. TMS and TCK are available for debugger connection. |
| FUNCTIONAL_4WJ | Pulldown | Pulldown | Pulldown | Fn4WJ | Functional development mode. In this mode, 4-pin JTAG is available to the developer. TDI, TMS, TCK, and TDO are available for debugger connection. |
| UARTLOAD_FUNCTIONAL_4WJ | Pulldown | Pullup | Pulldown | LDfrUART_Fn4WJ | Supports flash and SRAM load through UART and functional mode. The MCU bootloader tries to detect a UART break on UART receive line. If the break signal is present, the device enters the UARTLOAD mode, otherwise, the device enters the functional mode. TDI, TMS, TCK, and TDO are available for debugger connection. |
| RET_FACTORY_IMAGE | Pulldown | Pullup | Pullup | RetFactDef | When the device reset is toggled, the MCU bootloader kick-starts the procedure to restore factory default images. |
For SOP pullup/pulldown values, please refer to Boot Mode section of the data sheet.