Introduction to Questions 1-2 Dr. Schwartz has become frustr…
Introduction to Questions 1-2 Dr. Schwartz has become frustrated with non-UF students (e.g., non-paying students from around the world) utilizing educational material from his website and social media accounts, so he has decided to create a private platform similar to X (previously know as Twitter). (He is also not happy about the changes made at X over the last two years.) His new social media platform “37”, which for no good reason (like X) only allows users to make text posts consisting of at least one and at most 37 written ASCII characters, permits use just for his students. For the following two questions, you must help Dr. Schwartz by creating a proof of concept for the “37” platform. Ultimately, you must create some software that implements basic features of the platform. Since this is simply for a proof of concept, the software will target a simple computer system, namely, the OOTB µPAD. ———————————————————————————————————— Throughout Questions 1-2, assume the following: [1] The 32 kB external SRAM located on the OOTB Memory Base is already memory-mapped to the data memory space of the ATxmega128A1U and will be addressable via data memory locations 0xB0000 – 0xB7FFF. (In other words, you will not need to configure the EBI system.) [2] By way of the “C” function void create_text_post(void) (see Question 2), text posts consisting of at least one and at most 37 written ASCII characters are to be input from the computer connected to the µPAD and transmitted (using the Port D USART, USARTD0) to the aforementioned external SRAM, via the USART and DMAC systems of the microcontroller. The chosen DMA channel is to be manually triggered by software and is to transfer a complete text post once triggered. [3] The “C” character array text_post (i.e., text_post is of type char[]) will act as a buffer and store the latest text post. [4] It must be that no text post stored within external memory is overwritten. The first text post must start at data memory location 0xB004D, not 0xB0000. (Note: 0x4D = ‘M’.) [5] For simplicity, no memory location outside the aforementioned memory range for the external SRAM will ever be accessed.
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