Maestro: CSE466 Lab4 (Modified: Postpone Streaming to next week on advice from TA's...Thank your TA's).

Requirements:

1. From the serial UI, implement PLAY, PAUSE, and STOP commands for music contained in ROM.  Your system should be able to play at least from low A (~55Hz) to high F (~698Hz) which spans about 3.5 octaves, and sharps and flats must be included. See the spreadsheet for the countdown or overflow values. 

2. Demonstrate your player with a test sequence from ROM. It should be fairly short. For example, play an ascending scale on one channel and a descending one on another. This is primarily for debugging your player and for making sure that you understand the music format. You should  use only one timer for tone generation and timeslice management. 

3. Pick a song from http://www.knightvision.com/midis.html and convert it to .466 format. You'll need the mididmp.exe(NT) and mid2cse(UNIX) or mid2cse.exe(NT) tools. Put the song in ROM and play it. The Keil SW license limits you to 2K code size so you'll either have to cut the song short or get a dongle from the TA's or Chris Morgan to run the full license version of the SW. See implementation notes below for some suggestions.
4. Turn in:
   • Sign-off for parts 1-3
   • What is the worst case % of time spent in the ISR  (note that all of your time critical operations should be done in the ISR...the objective is to minimize your ISR, but not to make it artificially short by doing lots of time critical stuff in Main). For now, don't be concerned about optimizing your ISR. We will get to that next week.
   • What is your average % of time spent in the ISR (this can be an estimate based on your analysis of the code and assumptions about the data stream).
   • Write a paragraph or two about the implementation. What is your strategy? Turn in your code with comments.

Implementation Notes:

1. Most midi songs are split into several tracks, usually one for each instrument in the piece. The converter only translates one track at a time, so you'll have pick which one seems to represent the music best. Spot check the mididmp and mid2cse output files to see if they look okay to you.
2. Josh discovered a tool that allows you to view midi songs graphically and to combine separate tracks into one track. This is perfect if you want to combine a baseline or a drum track with a rhythm guitar track. The tool is called xxx, and is already installed on a few machines in the lab.
3. Danny wrote a program that converts .466 files from mid2cse into a C unsigned char array that you can paste into your code. The Keil eval software limits you to 2K code space, so your ROM test songs have to be fairly short or you can get the full license from the TA's or Chris Morgan.
4. Be careful with the format. Here is the final decision.
   • All songs start with a single byte to indicate time slice size in milliseconds (not tempo). You can ignore this byte if you want, but be careful to match your actual timeslice length with the parameter that you pass to mid2cse. A small amount of extra effort is need to support song specific timeslice length, and will improve portability and the range of songs that we can play.
   • In .466 format, a tone value of zero (0) means that the given channel is OFF. A tone value of 1 is the lowest A at ~55Hz. A tone value of 45 is the highest F at ~698Hz. Sharps and flats are included. If you want to support increased range, you will need to modify the mid2cse.c tool a little bit. I can show you how.
   • The only opcodes currently supported are f801 which is interpreted as a 31 TNE with no change to the currently played tones. f802 is interpreted as the end of the song.
5. Using the tools:
       mididmp song.mid > song.txt           // converts midi hex to midi text format.
       mid2cse song.txt 6 70 10 -1 song.466 > song.log
   • song.txt  is the text file output from mididmp
   • 6 is the track number that we want to convert to .466 format
   • 70 is the tempo at which we want our song to play
   • 10 is the number of milliseconds per timeslice. If this does not match your player then the song's tempo will either be fast or slower than the selected tempo when played.
   • -1 will shift all the notes in the song down one octave. This can also be positive or zero. Use this if the log file shows that there are many notes that are either too high or too low to play. If both happen then get another song!
   • song.466 is the hex file that Adam's program will stream out.
   • song.log is the log file. It shows all the too high, too low warnings. and it shows how many events are skipped due to lack of available channels. The log file also  interleaves the hex and event info so that you can study the output more easily.