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GPS NMEA, Failover Circuit upgrade attempt.
- Thread starter HellasTechn
- Start date
CDRIVE
Hauling 10' pipe on a Trek Shift3
Ash, I haven't done so myself but have you read any GPS NMEA posts on the Picaxe forum? While I like to keep things here at EP there is little doubt that the Picaxe forum will have pertinent data.
Chris
Sadlercomfort
Ash
Yeah but there's nothing useful, I've noticed some do use a max232 to convert logic levels.
Sadlercomfort
Ash
I think SERTXD command needs to be used, to send serial data back through the download cable and to the pc.
I think you need something like this below..
Code:
#picaxe 14m2
#DEFINE INPUT_PIN C.4
main:
GPS1_Read:
SERIN INPUT_PIN, N4800_4, ("$GPGSA,"),b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27
pause 1
SERTXD(b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27)
pause 1000
goto mainP.S Sorry for not replying sooner !
No worries.
I only use the serial download cable for downloading the program. then i move the picaxe to the breadboard and use 3 wires going to the computers DB9 connector.
PC pin2 connected to whatever transmit pin on picaxe, PC Pin3 connected to whatever receive pin on Picaxe and last PC pin5 to common ground wire
They do have some free software but does not cover my needs. I need a standalone device that can control the relay.
I will order a few and see what happens after i ge them.
Though i am not sure how to connect a Max232 with a picaxe but i am sure someone in the forum has done that before and can gude me !
Sadlercomfort
Ash
SERTXD is just for transmitting via the download cable my bad. You already made a SEROUT program which is similar to mine below:
Code:
#picaxe 14m2
#DEFINE INPUT_PIN C.4
#DEFINE OUTPUT_PIN B.1
main:
SERIN INPUT_PIN, N4800_4, ("$GPGSA,"),b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27
pause 1
SEROUT OUTPUT_PIN,N4800_4,(b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27)
pause 1000
goto mainI dont know why but it didn't work. I got nothing at all at the output.
It does work without the qualifier though and when i try to add the variable b28 after b27 it gives me the
Error: Unknown symbol - b28
Why ?
Here is the code that works :
main:
SERIN c.4, N4800_4, b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27
SEROUT B.5, N4800_4,(b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27)
goto main
I will check the data i get line by line and compare them to the original to see if they are correct. I will post logs here.
CDRIVE
Hauling 10' pipe on a Trek Shift3
Uh, that would be because b28 doesn't exist. M2 parts can provide "b" variables from b0 to b27. You can see this in the Variables Window incorporated in the editor.
Chris
Sadlercomfort
Ash
Perhaps try a different nmea sentence. . To see if the problem is the DOP sentence.
That makes sense.
Or it can not read the qualifier.
I will run tests tomorrow because it is already late
Sadlercomfort
Ash
Read up on the SerIn command in the pdf. I think it will light some bulbs in both of your wonderfully fertile young minds.
Chris
Which PDF Chris?
CDRIVE
Hauling 10' pipe on a Trek Shift3
Ash, Look in Manual 2 - (Basic Commands). I have a suspicion that the qualifier "$GPGSA," may have to be stored in a variable or constant and then reference the variable or constant. I'm deducing this because I didn't see anything in the SerIn description that even hinted that an ASCII or any other value, IE Numeric, Hex or Binary could be used directly.
I'm also curious about the qualifier's trailing Comma that's enclosed in the quotes. Is the Comma part of the qualifier string? If it isn't it shouldn't be within the quotes.
Chris
EDIT: Oops! I just found a qualifier example in the SerIn description using ASCII directly. Sorry about that.
I'm also curious about the qualifier's trailing Comma that's enclosed in the quotes. Is the Comma part of the qualifier string? If it isn't it shouldn't be within the quotes.
Chris
EDIT: Oops! I just found a qualifier example in the SerIn description using ASCII directly. Sorry about that.
Last edited:
Ok i have my test resaults.
It looks like that without the qualifier it can receive normally. The only issues in my very short test where with sentences GPGSV and GPGLL which are not sentences of interest for us.
I have run the GPGSV twice and GPGLL 3 times. GPLL came out correctly the very first time and last time also.
First line is what i have sent through termite and second line is what i got back. Second lines length is shorter due to limited number of variables.
It looks like that without the qualifier it can receive normally. The only issues in my very short test where with sentences GPGSV and GPGLL which are not sentences of interest for us.
I have run the GPGSV twice and GPGLL 3 times. GPLL came out correctly the very first time and last time also.
First line is what i have sent through termite and second line is what i got back. Second lines length is shorter due to limited number of variables.
Sadlercomfort
Ash
I have a feeling that we simply need to remove the $ from the qualifier, and we can just look for ("GPGSA") in ASCII. Try this below, executes the same:
The comma is always followed by $GPGSA in the sentence and therefore can be used. But we haven't used it in the main program. It was simply something else to try.
Code:
#picaxe 14m2 'Identify the PICAXE being used as an 14M2.
let b11 = 0 '
let b12 = 0
let b13 = 0
let b14 = 0
let b15 = 0
let b16 = 0
let b17 = 0
let b18 = 0
'The variables below have been assigned to labels, so now.. instead of writing b11 i can write GPS1_Data and the program automatically subsitutees b11 where the text GPS1_Data is written.
'This helps making the program readable and simple when lots of variables is used.
#DEFINE GPS1_Data b11
#DEFINE GPS1_Signal b12
#DEFINE GPS2_Data b13
#DEFINE GPS2_Signal b14
#DEFINE GPS1_Error b15
#DEFINE GPS2_Error b16
#DEFINE GPS1_DOP w10
#DEFINE GPS2_DOP w11
#DEFINE Buzzer C.0
#DEFINE Relay B.5
#DEFINE GPS1_SERIN C.4
#DEFINE GPS2_SERIN B.1
#DEFINE GPS1_BAD_DATA C.1
#DEFINE GPS2_BAD_DATA C.2
#DEFINE GPS1_TIMEOUT_LED B.4
#DEFINE GPS2_TIMEOUT_LED B.3
#DEFINE GPS1_TIMEOUT b17
#DEFINE GPS2_TIMEOUT b18
main: 'Start 'main' program.
GPS1_Read: 'Read GPSA Sentence from GPS1
SERIN[2000,TIMEOUT1], GPS1_SERIN, N4800_4, ("GPGSA"),b0,b0,b0,b1,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b2,b3,b4,b5
pause 1 '1us Delay
w10=b2-48*10+b4-48*10+b5-48 'Convert ASCII to Binary
pause 1 '1us Delay
GPS1_TIMEOUT=0 'Reset Timeout
LOW GPS1_TIMEOUT_LED 'Turns off gps1 timeout LED indicator at pin b.4
goto GPS1_Scan 'Read bits and quality of signal/data
GPS2_Read: 'Read GPSA Sentence from GPS1
SERIN[2000,TIMEOUT2], GPS2_SERIN, N4800_4, ("GPGSA"),b0,b0,b0,b6,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b7,b8,b9,b10
pause 1 '1us Delay
w11=b7-48*10+b9-48*10+b10-48 'Convert ASCII to Binary
pause 1 '1us Delay
GPS2_TIMEOUT=0 'Reset Timeout
lOW GPS2_TIMEOUT_LED ' Turns off gps2 timeout LED indicator at pin b.3
goto GPS2_Scan 'Read bits and quality of signal/data
TIMEOUT1:
Let GPS1_TIMEOUT=1
goto GPS1_Scan
TIMEOUT2:
Let GPS2_TIMEOUT=1
goto GPS2_Scan
GPS1_Scan:
if b1=49 then
Let GPS1_Signal=0 'if b1=1 then the GPS has no signal
endif
if b1=50 then
Let GPS1_Data=0 'if b1=2 then data might be missing or corrupt
Let GPS1_Signal=0
endif
if b1=51 then
Let GPS1_Signal=1 'if b1=3 we have signal and complete data
Let GPS1_Data=1 'if b0=44 there is a comma before DOP and thus complete data
endif
if b0!=44 then
Let GPS1_Data=0 'if b0 is not a comma (,) then data might be missing or corrupt
endif
'Error variable is held between 0 and 3. If more than 3 sentences are bad
'the value becomes 3 and the GPS is considered inactive. (Filters anomalies)
if GPS1_Signal=0 then
if GPS1_Error<3 then
inc GPS1_Error
endif
endif
if GPS1_Signal=1 then
if GPS1_Error>0 then
dec GPS1_Error
endif
endif
if GPS1_TIMEOUT=1 then
HIGH GPS1_TIMEOUT_LED ' turns on gps1 timeout led indicator at pinb.4
Let GPS1_Error=3
else
LOW GPS1_TIMEOUT_LED ' turns off gps1 timeout led indicator at pinb.4
endif
goto GPS2_Read 'Read GPSA Sentence from GPS2
GPS2_Scan:
if GPS1_TIMEOUT=1 then
High relay
endif
if b6=49 then
let GPS2_Signal = 0 'if b6=1 then the GPS has no signal
endif
if b6=50 then
Let GPS2_Data=0 'if b6=2 then data might be missing or corrupt
Let GPS2_Signal=0
endif
if b6=51 then
Let GPS2_Signal=1 'if b6=3 we have signal and complete data
Let GPS2_Data=1
endif
if b0!=44 then
Let GPS1_Data=0 'if b0 is not a comma (,) then data might be missing or corrupt
endif
'Error variable is held between 0 and 3. If more than 3 sentences are bad
'the value becomes 3 and the GPS is considered inactive. (Filters anomalies)
if GPS2_Signal=0 then
if GPS2_Error<3 then
inc GPS2_Error
endif
endif
if GPS2_Signal=1 then
if GPS2_Error>0 then
dec GPS2_Error
endif
endif
if GPS2_TIMEOUT=1 then
HIGH GPS2_TIMEOUT_LED ' turns on gps2 timeout led indicator at pinb.4
Let GPS2_Error=3
else
LOW GPS2_TIMEOUT_LED ' turns off gps2 timeout led indicator at pinb.4
endif
goto Active_GPS
Active_GPS:
if GPS1_Error =3 then
if GPS2_Error=3 then
HIGH Buzzer 'No active GPS, sound alarm
HIGH GPS1_BAD_DATA
HIGH GPS2_BAD_DATA
endif
if GPS2_Error<3 then
LOW Buzzer
HIGH Relay 'Set GPS2 as output
HIGH GPS1_BAD_DATA
LOW GPS2_BAD_DATA
endif
else
if GPS2_Error=3 then
LOW Buzzer
LOW Relay 'Set GPS1 as output
LOW GPS1_BAD_DATA
HIGH GPS2_BAD_DATA
endif
if GPS2_Error<3 then 'During this state DOP determines output if GPS1/2 Data ok
LOW Buzzer
LOW GPS1_BAD_DATA
LOW GPS2_BAD_DATA
if GPS1_Data=1 AND GPS2_Data=1 then 'Only compare DOP if both GPS data is complete with no errors
goto Active_DOP
endif
endif
endif
goto main
Active_DOP:
if GPS2_DOP < GPS1_DOP then 'If GPS2_DOP has lower DOP
HIGH Relay 'Set GPS2 as output
endif
if GPS1_DOP < GPS2_DOP then 'If GPS1_DOP has lower DOP
LOW Relay 'Set GPS1 as output
endif
pause 5000
goto main 'Go to 'main' program.The comma is always followed by $GPGSA in the sentence and therefore can be used. But we haven't used it in the main program. It was simply something else to try.
Sadlercomfort
Ash
Yes, I used this to understand how to write the first program and followed it closely. I see he also uses a max232. . When is your max232 arriving Constantine?
