ECE 493T9 Real Time Embedded System Tutorial Set 2 May 26, Spring 2008

Here is your TA Scott Chen Office Hour: Monday 4:00pm to EIT 3136 Assignment: UW-ACE Drop Box (Hardcopy) End of Tutorial (Softcopy)

Getting Started on New ES Tools in your hand: 1) ES Dev Kit / Custom-Assembled ES 2) Microcontroller User Manual 3) IDE Manual 4) ANSI-C Reference Handbook 5) Google Code Search 6) Your Design Idea How do you put these pieces together with your programming skills to realize your design?

ES Software Design Procedure 1)Identify the feature of your design. 2)Construct an abstract, conceptual block diagram, and convert all the blocks into logical ones. 3)Identify the functionalities provided by your microcontroller that are suitable for each of your logic blocks. !! What if your microcontroller does not provide the functionalities you need? Source external ICs that not only can provide the needed functions, but also have a compatible interface with your microcontroller.

ES Software Design Procedure Continue… 4) Find out the method of initializing all the design-required modules on the microcontroller. 5) Find out the proper ways to interact with the external ICs with your microcontroller. Above 2 steps gives you the Initialization Routine. (In C and / or Assembly) 6) Convert each of your logic block into procedural threads / subroutines, and combine them into RTOS or your own Assembly or C main routine. ==  Programming Complete

Why and When do you need UM? Starting step 2, you should have the following things ALWAYS sitting on your workbench: a) Your microcontroller user manual b) Data sheet of all the external ICs you need c) Instruction manual d) ANSI-C Referenece Handbook e) Customized C IDE manual You need a) and b) in order to understand the entire hardware platform you have, thereby enabling you to program with c), d), and e).

What does a UM provide you? uC standard and specialized features. uC pin layout and chip package diagram. uC voltage standards. - I/O standards for all the pins. - uC power rating. Reset conditions, power-saving modes, uC’s initial state upon power-up, etc... uC core data register set. - Can be very different among uC families. - in PIC18F2 family, only W. - in Motorola HC1x family, A, B, X, Y - What is the only core register that is common in all standard uCs? (Technically 2.)

What does a UM provide you? On-chip module introduction -Sync. and async. channels. -Timers -Specialized modules -You need this section to perform step 3) in the ES software design procedure. Memory Map -Directly related to your linker script. -Knowing the capability of your uC in memory management. -Very different among uC families.

What does a UM provide you? Control / Functional Register Sets -Beside core data registers, all other registers intended for module control and uC funtion selection are assigned with distinct address, with which you can read and/or write values from/to the registers via regular memory access in C and ASM. -3 Types: 1) Read Only: UART Rx Register 2) Write Only:UART Tx Register 3) Read & Write:Timer Configuration Register -You need to go through all the control register sets for your uC and properly initialize them in order to configure your uC to in the way you want. (It’s a Serious Mine Zone!!) -Possibly the most important part of the UM besides IM.

Instruction Manual The IM often comes as one large chapter in the UM. You may know ASM very well, but it doesn’t free you from reading IM for a new uC. (Sucks, I know.) Things that are different in IMs of different uC families: –Available Core Register Sets (from UM) –Available Addressing Modes –Available Instruction Sets –Notation Conventions uC functionalities are directly proportional to its size and is closely related to its intended purpose. Ex: You will not find instructions for sophisticated mathematical operations in a simple communication microcontroller.

Instruction Manual Common Addressing Modes: –Inheritant –Direct –Indexed –Indexed Indirect Not every uC has Indexed Indirect addressing mode. uCs with larger structures may have more advanced addressing modes for application-specific purposes. Ex: Zilog eZ80 family has a specialized extended 16-bit addressing mode, enabling the 8-bit processor to manage a larger memory map.

Instruction Manual Every uC family has distinct architecture, thus the number of cycle counts for two different uCs to perform the same instruction would differ. (Sometimes very significantly!) Every uC manufacturer develops its own ASM notation to remain “monopolistic competitive” (Just like the existence of DVD+R and DVD-R). It gives them the edge for making large profit, while leaving you system engineers to suffer longer learning curves. Conclusion:No matter how proficient you are in ASM programming, you cannot escape from re-learning every uC you come across throughout your engineering career. The bright side is that, once you have mastered the uC family, you get to fully exploit the functionalities it offers, leading to more efficient product designs as well as a higher salarylevel. =)

What’s Next? We Want a New Tutorial Time!!! 1)Mon 9:30am to DWE ) Wed 9:30am to DWE )Additional session available upon arrangement for those who cannot show up for these two time slots.

What’s Next? Assembly Programming Since everyone in the class has proficient experience in ASM and C, we will not cover any basics of ASM. (It will bore both you and me out anyways. =p) Instead, we will go through some special cases where ASM programming significantly outperforms C programming. We might also cover a bit on CRC check on-the-fly in both hardware and software designs.

Questions?