In my last entry, I posted an example in Spin that blinks an LED connected to the Propeller on and off 5 times. Some of you may have wanted to see the same example in ASM, so here you are (this time I commented everything so you can see what is going on. Also note that this example will loop forever, instead of only 5 times.):
' defines the start of a constants blockCON ' sets the special clock mode constant to use crystal input one and a phase ' locked loop (PLL) multiplier of 16. _clkmode = xtal1 + pll16x ' sets the input frequency of the clock to 5MHz _xinfreq = 5_000_000 ' defines a public function called Start. The first function in a ' file is the entry point for the program.PUB Start ' starts a new cog (ie. a core) which will run instructions starting ' at the given address cognew(@entry, 0) ' defines the start of a data sectionDAT ' sets the origin of all ASM code to the first address org 0 mov dira, 16 ' set pin 16 to output mode mov time, cnt ' initialize the time variable with the current clock add time, #9 ' add nine to the initial time variable' create a label called :loop:loop xor outa, 16 ' toggle the state of pin 16 (high or low) ' wait until the clock equals time, and then add delay to time waitcnt time, delay xor outa, 16 ' toggle the state of pin 16 (high or low) ' wait until the clock equals time, and then add delay to time waitcnt time, delay ' jump back to the loop label jmp #:loop' define a variable with a size of long with an initial value of 40,000,000delay long 40_000_000' reserve space for a variable with a size of one longtime res 1 On a different note, I purchased a handful of RCA connectors from Jameco so that I can connect the Propeller to the TV. Unfortunately, the leads don't fit into the breadboard, so I had to do a little hacking by adding some wire to the end of each lead.
I connected this to the Propeller through a four bit DAC (digital to analog converter) which allows me to blend the output of four separate pins into one composite NTSC signal. (I found a sample circuit for this on the Parallax website).
So now I have a TV output for my board. The next step is to get video going and to have something interesting to show for my efforts.
