Proper way to store and retrieve strings from DAT table?
WBA Consulting
Posts: 2,938
My current project (GPS based Scavenger Hunt) requires a data table that will store 3 pieces of data for 5 items that will be called in groups like in a table sort of like this:
String (clue)
Latitude
Longitude
Maidu Center
38.745843
-121.252334
Location2
38.739822
-121.252056
Location3
38.734363
-121.252490
Location4
38.732386
-121.252764
Last Location
38.736832
-121.252886
I have been laying around with the DAT section code from page 109 of the Propeller Education Kit labs book. However, even though I can store a string with a byte size alignment without issue, I can't figure out how to retrieve just a single string in an array. In other words, if this is my DAT section:
Then how do I pull the second string (clue2) to send to an LCD? All of my attempts to pick one item, just shoot out everything under cluedata; all I can get is "clue1clue2clue3" on the LCD.
Also, how do is store the lat/long? Can I store 38.734363 in a DAT array and have it be usable for my great circle math formulas?
Lastly, if I want the user of my code to have an easy way to modify the code to their clues, latitudes, longitudes, is there a better way than a DAT array?
String (clue)
Latitude
Longitude
Maidu Center
38.745843
-121.252334
Location2
38.739822
-121.252056
Location3
38.734363
-121.252490
Location4
38.732386
-121.252764
Last Location
38.736832
-121.252886
I have been laying around with the DAT section code from page 109 of the Propeller Education Kit labs book. However, even though I can store a string with a byte size alignment without issue, I can't figure out how to retrieve just a single string in an array. In other words, if this is my DAT section:
DAT ClueData byte "clue1", "clue2", "clue3", 0
Then how do I pull the second string (clue2) to send to an LCD? All of my attempts to pick one item, just shoot out everything under cluedata; all I can get is "clue1clue2clue3" on the LCD.
Also, how do is store the lat/long? Can I store 38.734363 in a DAT array and have it be usable for my great circle math formulas?
Lastly, if I want the user of my code to have an easy way to modify the code to their clues, latitudes, longitudes, is there a better way than a DAT array?
Comments
CON _clkmode = XTAL1|PLL16X _xinfreq = 5_000_000 OBJ serial: "FullDuplexSerial" PUB null | n serial.start(31, 30, %0000, 115200) waitcnt(clkfreq*3 + cnt) repeat n from 0 to 2 serial.str(@@clue_T[n]) serial.tx(13) DAT clue_T word @clue_0, @clue_1, @clue_2 clue_0 byte "1st clue", 0 clue_1 byte "2nd clue", 0 clue_2 byte "3rd clue", 0Thanks, that did the trick. I now have tables squared away for the clues, latitudes, and longitudes. Also, since the byte aligned string data will flow out together, I added in some hex codes for the LCD so each clue handles it's own positioning. ( IE: $0c is CLS which positions on the first row, position 0, and $94 is position 0 on the 2nd row). So that I have default lat/longs in the code, I just filled all 5 with Parallax's lat/long. Clue_0 is basically a null because I am using it to determine if it is the first time the unit is powered up so I know whether or not to display instructions.
Here's the DAT table:
And to call out the clues, I am using the following code (EEDATA[2] is the current clue number. I save an array of variables to EEPROM so that powering down doesn't reset you to the first clue):
Thanks to your help, all I have to do now is merge my EEPROM storage/retrieval code, Splash screen code, and my GPS distance measuring code. Since they are all done and working separately, it should be fairly easy from here on out.
DAT clue_T word @clue_0, @clue_1, @clue_2, @clue_3, @clue_4, @clue_5 ' Parallax = 38.813195,-121.296108 clue_0 long 0 long 0 byte "Start", 0 clue_1 long 38.813195 long -121.296108 byte $0c, "1st", $94, " clue", 0 clue_2 long 38.813195 long -121.296108 byte $0c, "2nd", $94, " clue", 0 clue_3 long 38.813195 long -121.296108 byte $0c, "3rd", $94, " clue", 0 clue_4 long 38.813195 long -121.296108 byte $0c, "4th", $94, " clue", 0 clue_5 long 38.813195 long -121.296108 byte $0c, "5th", $94, " clue", 0In this case latitude is long[@@clue_T[n]][0], longitude is long[@@clue_T[n]][1] and the string address is @@clue_T[n] + 8.Thanks again for the help. Last night I completed the data table section of my code using your suggestions and it works well. I even had time to work on some of the GPS distance math using coordinates from the data table and it worked clean as well. I have a weird issue with the LCD, but I believe I may be missing some delays somewhere in my code. The backlight will flicker once in a while as if I am turning it off/on really quick and a few times it never displayed anything until I reset the prop a second time.
I've had times when I've needed to know this offset to use it other ways.
I believe this offset is always 16 but I'm not sure.
This is how I computed the offset when needed (using your example data).
PUB GetOffset result := @clue_0 - clue_T[0] DAT clue_T word @clue_0, @clue_1, @clue_2 clue_0 long 0 long 0 byte "Start", 0 clue_1 long 38.813195 long -121.296108 byte $0c, "1st", $94, " clue", 0 clue_2 long 38.813195 long -121.296108 byte $0c, "2nd", $94, " clue", 0The method "GetOffset" should return the offset value.
Hoping to have my prototype done soon. I have it completely build (but with a Quickstart and PMB-648 GPS) and my latest version of code is about 90% complete. Just have to figure out a bug with how my code validates when the GPS flags that it has a valid fix and do a few more minor tweaks. I will be buying one of the new VPN1513 GPS modules, product 28510, to make a second unit. The total cost of the project will be under $100 now that the Propeller and GPS is only $35.