The maximum clock frequency of the TM4C1236D5PMIR is 80 MHz, but it can be overclocked to 120 MHz with some limitations.
The pin muxing on the TM4C1236D5PMIR can be configured using the Pin Mux Utility tool provided by Texas Instruments, or by manually setting the registers in the Pin Control module.
The main difference between the TM4C1236D5PMIR and the TM4C1294NCPDT is that the TM4C1294NCPDT has more flash memory (1MB vs 256KB) and more peripherals, such as a USB OTG interface and a CAN interface.
The ADC on the TM4C1236D5PMIR can be used by configuring the ADC module registers, selecting the input channel, and triggering the conversion using a software trigger or an external trigger.
Yes, the TM4C1236D5PMIR can be used with an operating system like Linux or FreeRTOS, but it requires porting the OS to the specific microcontroller and configuring the peripherals and drivers accordingly.