strange problem with HSERIN

[Archangel]

Hi Beginner,
One thing to check is the port's idle state. HSER* requires the port to idle HIGH so you will need a pull up resistor or the port will likely hang the program.

[malc-c]

One thing to check is the port's idle state. HSER* requires the port to idle HIGH so you will need a pull up resistor or the port will likely hang the program.

Joe,

Thanks for the heads up on that, but most of the samples I've come across have something like

 IF RCIF THEN GOSUB xxxxx
or
 IF RCIF=1 THEN GOSUB xxxxx

If the pins are tied high then this will cause the code to constantly loop to the sections that deal with the comms. would it not be better to tie the pins to ground via resistors ?

[Bruce]

The USART RX pin should definitely idle high, but this routine has some major issues;

BEGIN: 
   For K = 240 TO 240  ' <-- BIG problem here
    teller = teller + 1   
    ADRESS = K
    AANTAL = 1 
    buffero(K) = teller  ' <-- there is no buffero(240)
    GoSub WEGSCHRIJVEN
    PauseUs 200
    ADRESS = K
    AANTAL = 1 
    GoSub OPHALEN 
    IF OK = 1 Then
     lcdbufO(K) = bufferi(K) ' <-- same issue here
     LCDBUFI(K) = BUFFERO(K) ' <-- and here
     GoSub LCD 
     OK = 0
    GoTo HIER1
    EndIF
   LCDBUFO(K) = 0
   LCDBUFI(K) = 0
   GoSub LCD
HIER1:  Next

K = 240, but your largest array variables are only 6 bytes. I.E. buffero(0) to buffero(5) would be the last byte available in your buffero array.

[malc-c]

Uhmm... just looked at the schematic in the EasyPIC5 manual, the RX line is connected direct to the R1Out pin on the Max232 - the TX pin to the T1in pin which is tied to Vcc via 1K resistor. I assume the MAX232 will handle the logic level of the RX pin ?

[Bruce]

I assume the MAX232 will handle the logic level of the RX pin ?

Yes it will. The MAX232 has an internal pull-down on the R1in side of the inverter http://www.rentron.com/Files/bMAX232.gif

[Beginner]

The USART RX pin should definitely idle high, but this routine has some major issues;

BEGIN: 
   For K = 240 TO 240  ' <-- BIG problem here
    teller = teller + 1   
    ADRESS = K
    AANTAL = 1 
    buffero(K) = teller  ' <-- there is no buffero(240)
    GoSub WEGSCHRIJVEN
    PauseUs 200
    ADRESS = K
    AANTAL = 1 
    GoSub OPHALEN 
    IF OK = 1 Then
     lcdbufO(K) = bufferi(K) ' <-- same issue here
     LCDBUFI(K) = BUFFERO(K) ' <-- and here
     GoSub LCD 
     OK = 0
    GoTo HIER1
    EndIF
   LCDBUFO(K) = 0
   LCDBUFI(K) = 0
   GoSub LCD
HIER1:  Next

K = 240, but your largest array variables are only 6 bytes. I.E. buffero(0) to buffero(5) would be the last byte available in your buffero array.

I tried to change the For K = 240 TO 240 to For K = 0 TO 5 , but it does not make any difference.

The chip still keeps running VERY slow (like 25 seconds startup time) when I'm using the HSERIN command.

---------------------

The RS232 schematic is ok, I'm using the same for other PCB's with 16f887 and 16f882 chips where it works fine.
----------------------

Also changing the bit TRISG<2> = 1 does not solve this problem.

Any more suggestions?

[mat janssen]

I did some tests with that chip and also using a rs485 chip to test. You talked about rs232 and a direction (TX_ENABLE) and when I look at the code I think it's RS485, but that is not an issue.
I also discovered that indeed the chip will not startup when using HSERIN and the RX pin of the uart is high.
I put a 10K resistor from the RX pin of the picchip to ground and now the program is starting up normaly.
I hope it will help you.