[fpc-pascal] TFPTimer does not fire, why?
Ì have a problem using TFpTimer on Linux (FPC 3.0.4, Lazarus 2.0.8 on
Raspbian).
The application is a small GUI test app where I have added a timer in
order to update the display with incoming data.
So I have it set up like this:
{$mode Delphi}
interface
uses
...
fptimer,
...
type
TfrmMain = class(TForm)
...
private
FTimCheckInputs: TFpTimer;
...
procedure OnTimCheckInputs(Sender: TObject);
...
implementation
procedure TfrmMain.FormCreate(Sender: TObject);
begin
...
FTimCheckInputs := TFpTimer.Create(NIL);
FTimCheckInputs.OnTimer := OnTimCheckInputs;
FTimCheckInputs.Interval := 500; // 500 ms latency
...
end;
procedure TfrmMain.OnTimCheckInputs(Sender: TObject);
begin
ShowInByte; //<== This is NEVER reached!
end;
procedure TfrmMain.btnOpenComClick(Sender: TObject);
begin
...
if FRemote.OpenPort(edComPort.Text, StrToInt(cbxBaud.Text)) then
begin
...
FTimCheckInputs.Enabled := true;
end
else
begin
...
FTimCheckInputs.Enabled := false;
end;
end;
procedure TfrmMain.FormClose(Sender: TObject; var CloseAction:
TCloseAction);
begin
FTimCheckInputs.Enabled := false;
FTimCheckInputs.Free;
...
end;
When I click the btnOpenCom button I get to the button event and the
code reachers the line:
FTimCheckInputs.Enabled := true;
So presumably here the timer should start and fire after 500 ms as set
up in the FormCreate procedure.
But it never does! I do not get into this at all. I have put a
breakpoint there but it never fires, whereas other breakpoints do fire
so I can see that for example btnOpenComClick fires off properly and
the timer should be enabled.
And before you ask, I *have* this at the beginning of the lpr file:
uses
{$IFDEF UNIX}
cthreads,
{$ENDIF}
Why does the FpTimer event not fire?
I am assuming the Interval property is in milliseconds...
When I step through the code and reach the place where the timer is
enabled the text that appears when I hover over the Enabled keyword is
very strange:
"FTimCheckInputs.Enabled = TYPE FPTIMER has no component named
ENABLED.
published property TFPTimer.Enabled:Boolean"
Is it not possible to start the timer using Enabled?
--
Bo Berglund
Developer in Sweden
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Re: [fpc-pascal] TFPTimer does not fire, why?
On Mon, 7 Sep 2020, Bo Berglund via fpc-pascal wrote:
Ì have a problem using TFpTimer on Linux (FPC 3.0.4, Lazarus 2.0.8 on
Raspbian).
The application is a small GUI test app where I have added a timer in
order to update the display with incoming data.
So I have it set up like this:
{$mode Delphi}
interface
uses
...
fptimer,
...
type
TfrmMain = class(TForm)
...
private
FTimCheckInputs: TFpTimer;
...
procedure OnTimCheckInputs(Sender: TObject);
...
implementation
procedure TfrmMain.FormCreate(Sender: TObject);
begin
...
FTimCheckInputs := TFpTimer.Create(NIL);
FTimCheckInputs.OnTimer := OnTimCheckInputs;
FTimCheckInputs.Interval := 500; // 500 ms latency
...
end;
procedure TfrmMain.OnTimCheckInputs(Sender: TObject);
begin
ShowInByte; //<== This is NEVER reached!
end;
procedure TfrmMain.btnOpenComClick(Sender: TObject);
begin
...
if FRemote.OpenPort(edComPort.Text, StrToInt(cbxBaud.Text)) then
begin
...
FTimCheckInputs.Enabled := true;
end
else
begin
...
FTimCheckInputs.Enabled := false;
end;
end;
procedure TfrmMain.FormClose(Sender: TObject; var CloseAction:
TCloseAction);
begin
FTimCheckInputs.Enabled := false;
FTimCheckInputs.Free;
...
end;
When I click the btnOpenCom button I get to the button event and the
code reachers the line:
FTimCheckInputs.Enabled := true;
So presumably here the timer should start and fire after 500 ms as set
up in the FormCreate procedure.
But it never does! I do not get into this at all. I have put a
breakpoint there but it never fires, whereas other breakpoints do fire
so I can see that for example btnOpenComClick fires off properly and
the timer should be enabled.
And before you ask, I *have* this at the beginning of the lpr file:
uses
{$IFDEF UNIX}
cthreads,
{$ENDIF}
Why does the FpTimer event not fire?
Do you call checksynchronize at regular intervals ? The default timer is
threaded, and the OnTimer event is called in the main thread. For this to
work, you need to call checksynchronize at regular intervals in your main
thread.
Michael.___
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Re: [fpc-pascal] TFPTimer does not fire, why?
On Mon, 7 Sep 2020 12:40:07 +0200 (CEST), Michael Van Canneyt via fpc-pascal wrote: >> Why does the FpTimer event not fire? > >Do you call checksynchronize at regular intervals ? The default timer is >threaded, and the OnTimer event is called in the main thread. For this to >work, you need to call checksynchronize at regular intervals in your main >thread. Before I read your reply I tested another thing: I dropped a regular timer from the component palette onto the form intending to use that instead of FpTimer. So I made an event function by doubleclicking the event as usual and added the same call there. I set the new timer to disabled by default so I can enable it on successful port open like the FpTimer. Once all that was done I again stepped through the application with breakponts in both event functions and amazingly the FpTimer event now fired! And after it was done the new timer also called its event... In fact it now seems to work where it did not before. So next I *removed* the newly dropped timer and its references in the code and now the FpTimer still works. How very strange! Concerning calling CheckSynchronize I do not really know where it can be done... I think you do not mean that I should put a timer on the main form and then in its OnTimer event call CheckSynchronize? This program is a GUI application and I do not know where one could put a call like that. -- Bo Berglund Developer in Sweden ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TFPTimer does not fire, why?
On Mon, 7 Sep 2020, Bo Berglund via fpc-pascal wrote: On Mon, 7 Sep 2020 12:40:07 +0200 (CEST), Michael Van Canneyt via fpc-pascal wrote: Why does the FpTimer event not fire? Do you call checksynchronize at regular intervals ? The default timer is threaded, and the OnTimer event is called in the main thread. For this to work, you need to call checksynchronize at regular intervals in your main thread. Before I read your reply I tested another thing: I dropped a regular timer from the component palette onto the form intending to use that instead of FpTimer. That is because you then add the LCL to the application, and in their application object, they call checksynchronize on idle. Even if you remove the LCL timer, the checksynchronize still will do it's job. Michael. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to implement a circular buffer object in pascal?
Bo, Most of the users on this forum have never interfaced with hardware , as you can see from the responses. Those who have interfaced with hardware have developed circular buffers which they know work , and they reuse them again and again. I will describe in general terms the structure a circular buffer implemented to receive data , as it is usually more difficult to received the data than to send it due to the asynchronism between the sender and receiver. It has been used for many years , starting in 16bit-DOS , the 32bit-DPMI using interrupt handlers , then Linux using threads. The concept is the same for versions. The following assumes you are receiving data from a sender , and in this case the sender and receiver are connected via 1Gbps Ethernet using Synapse (works really well). A thread receives data into an array of byte. RxBuffer : Array[0..1500] of byte ... and copies the number of bytes received into a circular buffer , which is an array of RxBuffer. In pseudo code it looks like this ... CircularBuffer : Array[0..N] of RxBuffer There is a ReadIndex and a WriteIndex , both longword or longint. The thread moves the data into the circular buffer continuously increase the WriteIndex each write of RxBuffer data. If the WriteIndex > N then WriteIndex := 0 , otherwise it is increased by 1. The main loop (below) moves the byte data using MOVE from CircBuffer to whatever structure it represents , increase the ReadIndex by one and decodes the data as needed. If ReadIndex <> WriteIndex then .. do the work as described above and increment the ReadIndex I use the Free Pascal unit which allows suspending the thread while the ReadIndex is being increased. In the old DOS/DPMI days we would disable interrupts briefly. If you are innterested I can send you code snippets showing exactly how to implement the circular buffer. Regards Brian -- Sent from: http://free-pascal-general.1045716.n5.nabble.com/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
[fpc-pascal] Why can I not build fpc 3.0.4 with ppcarm 3.0.0 or 3.0.4?
I have a script I use all the time to install FPC/Lazarus on Raspberry Pi units when I configure for development. Today when I was setting up a Raspberry PiZero I was hit with this message when I was going to build fpc 3.0.4 (sources checked out from svn): Makefile:2790: *** The only supported starting compiler version is 3.0.2. You are trying to build with .. Stop. The script downloads ppcarm from my website where I have stuffed 3.0.0 in a tar archive to use for this purpose. Has worked on more than 10 RPi units so far. I never before saw a requirement for ppcarm 3.0.2... Anyway I know that fpc can build itself so I made an archive for ppcarm 3.0.4 and uploaded that to the website and modified the script. But no go, same message... Any ideas? -- Bo Berglund Developer in Sweden ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Ethernet Relays
When I try to compile either of the examples below, I get Error: Identifier not
found "ESocketError"
Any ideas?
James
Yes, catch the ESocketError in a try..except:
Try
S:=TFPHTTPCLIENT.SIMPLEGET('http://10.10.01.01/3/15');
except
On E: ESocketError do
Writeln('Could not connect to server'); end;
> Is there a way to change the amount of time before the timeout?
Yes, but then you need to create an instance, i.e. the Simple* commands won't
do that for you:
Instead, it will look like this:
uses fphttpclient;
Var
C : TFPHTTPClient;
begin
C:=TFPHTTPClient.Create(Nil);
try
try
C.ConnectTimeout:=10; // Or whatever you think is good
C.Get('http://10.10.01.01/3/15');
except
On E: ESocketError do
Writeln('Could not connect to server');
end;
finally
C.Free;
end;
end;
Michael.
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Re: [fpc-pascal] Why can I not build fpc 3.0.4 with ppcarm 3.0.0 or 3.0.4?
On Tue, 08 Sep 2020 00:59:51 +0200, Bo Berglund via fpc-pascal wrote: >Today when I was setting up a Raspberry PiZero I was hit with this >message when I was going to build fpc 3.0.4 (sources checked out from >svn): > >Makefile:2790: *** The only supported starting compiler version is >3.0.2. You are trying to build with .. Stop. > It turns out that this was a grossly misleading error message! The real problem was that the RPiZero is arm v6 and the seed compiler downloaded was arm v7! After changing to ppcarm 3.0.0 for arm6 the build works. -- Bo Berglund Developer in Sweden ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Ethernet Relays
Add the ssockets unit to your uses clause.
Michael
On Mon, 7 Sep 2020, James Richters via fpc-pascal wrote:
When I try to compile either of the examples below, I get Error: Identifier not found "ESocketError"
Any ideas?
James
Yes, catch the ESocketError in a try..except:
Try
S:=TFPHTTPCLIENT.SIMPLEGET('http://10.10.01.01/3/15');
except
On E: ESocketError do
Writeln('Could not connect to server'); end;
Is there a way to change the amount of time before the timeout?
Yes, but then you need to create an instance, i.e. the Simple* commands won't
do that for you:
Instead, it will look like this:
uses fphttpclient;
Var
C : TFPHTTPClient;
begin
C:=TFPHTTPClient.Create(Nil);
try
try
C.ConnectTimeout:=10; // Or whatever you think is good
C.Get('http://10.10.01.01/3/15');
except
On E: ESocketError do
Writeln('Could not connect to server');
end;
finally
C.Free;
end;
end;
Michael.
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