How to stop a program HSERIN blocking

Thread Starter

camerart

Joined Feb 25, 2013
2,113
Hi,
EDITED:
I'm using HSERIN an a program, but it blocks
How do I stop this please?
As this has been edited, some early replies, may look confusing.
Camerart.
 
Last edited:

ericgibbs

Joined Jan 29, 2010
10,846
hi C,
We already use one version in your programs.
E

getmsg: 'read
If PIR1.RCIF = 0 Then Goto getmsg
char = RCREG
............................
 

Thread Starter

camerart

Joined Feb 25, 2013
2,113
Hi E and I,
I found the [ getmsg ] programs, and now understand how to use it.

I tested HSERGET instead of HSERIN and it works fine, especially, as sometimes a message starts then gets garbled, and HSERGET READS it, so some DATA can be collected

At the moment I'm checking using the Simulator and at this point;
--------------------------------------------------------------------------------------------
Hserget char
If char = "$" Then 'start
str1(0) = char
str2(0) = char
rxi = 1
Else
Goto skip1
Endif
------------------------------------------------------------------------
if I mess up the beginning of the message which starts with [ $ ] then it goes to [ skip1 ] but leaves the rest of the message blocking the [ Hardware UART sim ]
Will this be the same LIVE (I'll be LIVE testing later.)
Thanks,
C.
 

ericgibbs

Joined Jan 29, 2010
10,846
hi C,
As your serial inputs are not synchronised, recall what we had to do sometime ago.
If the RX buffer gets buffer gets data and it is not Read, then the OERR flag is set, if you do not test for this flag, when you read the buffer it could be 'old' rubbish data.
We used the following routine.

get_neo:
If RCSTA.OERR = 1 Then 'if over run error then flush RXD buffer
RCSTA.CREN = 0
RCSTA.CREN = 1
char = RCREG
char = RCREG
PIR1.RCIF = 0
Endif

sync1: 'wait for a $ start of string
If PIR1.RCIF = 0 Then Goto sync1
char = RCREG
If char <> 0x24 Then Goto sync1 '$'
str1(1) = char
rxi = 2
 

Thread Starter

camerart

Joined Feb 25, 2013
2,113
hi C,
As your serial inputs are not synchronised, recall what we had to do sometime ago.
If the RX buffer gets buffer gets data and it is not Read, then the OERR flag is set, if you do not test for this flag, when you read the buffer it could be 'old' rubbish data.
We used the following routine.

get_neo:
If RCSTA.OERR = 1 Then 'if over run error then flush RXD buffer
RCSTA.CREN = 0
RCSTA.CREN = 1
char = RCREG
char = RCREG
PIR1.RCIF = 0
Endif

sync1: 'wait for a $ start of string
If PIR1.RCIF = 0 Then Goto sync1
char = RCREG
If char <> 0x24 Then Goto sync1 '$'
str1(1) = char
rxi = 2
Hi E,
We changed the [ get_neo ] to [ get_data ] where some changes were made, here is what is used at the moment:
I notice there isn't [ PIR1.RCIF ] in the later CODE.

Is there a reason for the second [ char = RCREG ] marked with XXXXXXXXXXXXXX
C.
Code:
------------------------------------------------------------------------------------
get_data:
'Await GPS RXD -----------------GPS RMC ----------------------
''''''PASTE: $GNRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A?
'''OR PASTE: $REMOTE,1100,1200,1300,1400,1500,1600,?

If RCSTA.OERR = 1 Then  'if over run error then flush RXD buffer
    RCSTA.CREN = 0
    RCSTA.CREN = 1  'ENABLES RECEIVER
    char = RCREG
    char = RCREG  'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
    Hserout "RX Err!", CrLf
    Goto skip1
Endif
'Hserin char
'HSERGET TEST
Hserget char
If char = "$" Then  'start
    str1(0) = char
    str2(0) = char
    rxi = 1
Else
    Goto skip1
Endif

nxt_rxin:
    Hserin char
    If char = "?" Or char = 0x0a Then Goto msg_eol
    str1(rxi) = char  'Set to only use str1 or 2
    str2(rxi) = char
    'Hserout str1(rxi)  'show for testing only
    rxi = rxi + 1
Goto nxt_rxin
    'Hserout CrLf

msg_eol:  'Sends received and saved message via HSEROUT
    strtim = ""
    strlat = ""
    strlat = ""
    strlong = ""
    strtp = ""
    strpr = ""
    msg1 = ""
------------------------------------------------------------------------------------------------------
Mod edit: code tags
 
Last edited by a moderator:

BobaMosfet

Joined Jul 1, 2009
1,209
Where's your flowchart. Do you understand how to actually manage trains of data, and parsing, or are you still at the spaghetti code stage?
 

Thread Starter

camerart

Joined Feb 25, 2013
2,113
Where's your flowchart. Do you understand how to actually manage trains of data, and parsing, or are you still at the spaghetti code stage?
Hi B,
I learnt spaghetti BASIC in the 80s by watching my son programming a Zx Spektrum, and never advanced, sadly. I can assure you that I've tried.
I get advice from members of this type of forum, saving snippets of CODE, and pasting them into new programs, where they are corrected as in this example.
I adapt what I want as I go along, there is no flowchart.
P.S The program I'm [we're) on at the moment has taken a couple of years so far:)
C
 
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Thread Starter

camerart

Joined Feb 25, 2013
2,113
hi C,
When a OERR is flagged I have found it wise to do a double RX Bfr read.
Look at this link
https://www.microchip.com/forums/m1035054.aspx

Most datasheets advise to toggle CREN and to read RCREG a couple of times.
Hi E,
Char = RCREG----------OK

Am I correct that because of the above there is no need for [ PIR1.RCIF ] ?
C.
---------------------------------------------------------------------
FROM D/S:
RCIF: EUSART Receive Interrupt Flag bit 1 = The EUSART receive buffer, RCREG, is full (cleared when RCREG is read) 0 = The EUSART receive buffer is empty
---------------------------------------------------------------------
 

ericgibbs

Joined Jan 29, 2010
10,846
hi C,
It depends upon how your program is written.
If you do not have the On UART RX, Interrupt Enabled and you wanted to check if a UART char had been received, the program would check the RCIF flag.
If RCIF=1, then to ensure that an RX Bfr Over Flow Error had not occurred [ while the program had been off doing other things] check the OERR.
If the EORR =0 then read the incoming msg until <crlf>
ELSE
RCSTA.CREN = 0
RCSTA.CREN = 1
char = RCREG
char = RCREG
PIR1.RCIF = 0 ; clear the RCIF flag, which had been set by the earlier ERR data.

; and either wait for the next incoming msg IDENT and read the full msg,,,,, OR go do something else
E
 

Thread Starter

camerart

Joined Feb 25, 2013
2,113
Hi,
In the simulator, the program isn't blocking, but the UART is.

When there is no $ at the beginning of the sentence, it jumps to [ SKIP1 ] Is there something I could put there to clear the UART?

C
 

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Thread Starter

camerart

Joined Feb 25, 2013
2,113
Hi,
I've tried the simulator where #15 is true.

LIVE tests:
Using HSERGET does keep the program flowing allowing the other modules (Compass etc) are serviced, but doesn't appear to process the CHARS so I think HSERIN has to be used. Any comments?

Using HSERIN, as shown in the simulator the UART blocks.

IMPORTANT NOTE:
In the program I use a DATA SWITCH to switch between the GPS and 'BASE/REMOTE', each INPUT switches to the other as each is READ
C
 
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Thread Starter

camerart

Joined Feb 25, 2013
2,113
Hi,
Reading #14 again, Am I correct that [ On UART RX ] would need a TIMER? If so then I don't have it set, would it be better if I did?.

Here is the bottom of the MAIN LOOP, showing the GOTO and the SUBROUTINE.
C.
 

Attachments

ericgibbs

Joined Jan 29, 2010
10,846
hi C,
You are Exiting a GOTO call to subroutine with a RETURN.
Its the Program thats hanging not the UART
E

get_data:
If RCSTA.OERR = 1 Then 'if over run error then flush RXD buffer
RCSTA.CREN = 0
RCSTA.CREN = 1 'ENABLES RECEIVER
char = RCREG '1
char = RCREG '2
PIR1.RCIF = 0 'clear the RCIF flag, which had been set by the earlier err data.
Hserout "RX Err!", CrLf
Goto skip1 ' ?????????????????????????????????
Endif
......................................................................
skip1:

For x = 0 To 79
str1(x) = 0
Next x

For x = 0 To 79
str2(x) = 0
Next x


Return '???????????????????????????????
 

Thread Starter

camerart

Joined Feb 25, 2013
2,113
hi C,
You are Exiting a GOTO call to subroutine with a RETURN.
Its the Program thats hanging not the UART
E

get_data:
If RCSTA.OERR = 1 Then 'if over run error then flush RXD buffer
RCSTA.CREN = 0
RCSTA.CREN = 1 'ENABLES RECEIVER
char = RCREG '1
char = RCREG '2
PIR1.RCIF = 0 'clear the RCIF flag, which had been set by the earlier err data.
Hserout "RX Err!", CrLf
Goto skip1 ' ?????????????????????????????????
Endif
......................................................................
skip1:

For x = 0 To 79
str1(x) = 0
Next x

For x = 0 To 79
str2(x) = 0
Next x


Return '???????????????????????????????
Hi E,
The RETURN is returning to the earlier [ Gosub get_data ] See #17
C.
 
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Thread Starter

camerart

Joined Feb 25, 2013
2,113
Hi,
As each test using the fantastic simulator takes quite a while, I quite often loose track of what I'm testing (Even with notes) So I tend to test LIVE for this.

Today I woke up with a FLOWCHART in my head, but while I can 'see' it, I can't tell if it would work as a program.

Using the example in #17, I understand how each element works (Almost!) Here is what I want to try, and I think I can write it.
-------------------------------------------------------------------------------------------------
Use the [ If RCSTA.OERR = 1 Then ] section at the beginning.

[ If char = "$" Then ] start LOOP of this until>
[ If str1(1) = "R" Then ] section, then look for that sentence [ ? ]
OR
[ If str1(5) = "C" or "R" Then ] section, then look for that sentence [ ? ]

(Now that sentence is in STR1 or 2) switch [ DATASWITCH ] to look for the alternate type of sentence, while processing this sentence. (This would hopefully save going though all of the approx 10x NMEA sentences when checking the GPS)

If either type of sentence are not RECEIVED then use an INTERRUPT to switch the DATASWITCH until one or the other sentence is RECEIVED.

I hope this is clear, I'll keep checking, while I attempt to write this, if someone would check the flow please?

EDIT: MARKED BOLD
C.
----------------------------------------------------------------------------------------------------
 
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