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karth
Joined: 10 Sep 2003
Posts: 29
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| migrating 18f452 to pic18LF4525 uart to EUSART problem |
 Posted: Fri Jun 13, 2008 10:50 am |
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guys i need some guidance with this,
I am switching mcu from 18f452 to 18LF4525
rock = 20Mhz
vdd = 3.4Vdc
ccs compiler=3.236
mplab ide= v8.0
tools= real ice
i have done 80% percent of the work... and i am stuck with the uart.
tx is working
rx not working
with the 18f452 the code was 100% working...so im pretty sure is not the code it got to do with some configuration, am i right?
any pointer???
| Code: | #include <18F4525.h>
#device adc=10
#FUSES HS
#FUSES WDT //No Watch Dog Timer
#FUSES NOPROTECT //Code not protected from reading
//#FUSES NOOSCSEN //
#FUSES NOWDT //
#FUSES CCP2C1 //
#FUSES NOBROWNOUT //Reset when brownout detected
#FUSES PUT //No Power Up Timer
#FUSES NOCPD //No EE protection
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOLVP //Low Voltage Programming on B3(PIC16) or B5(PIC18)
#FUSES NOWRT //Program memory not write protected
#FUSES NOWRTD //Data EEPROM not write protected
#FUSES NOWRTC //configuration not registers write protected
#FUSES NOWRTB //Boot block not write protected
#FUSES NOEBTR //Memory not protected from table reads
#FUSES NOEBTRB //Boot block not protected from table reads
#FUSES NOCPB //No Boot Block code protection
#FUSES NOPROTECT
#fuses HS,WDT128,NOPROTECT,PUT,NOBROWNOUT,NOLVP
#use delay(clock=20000000)
#use i2c(Master,sda=PIN_C4,scl=PIN_C3, FORCE_HW, SLOW) // hw I2C
#use rs232(baud=4800,xmit=PIN_C6,rcv=PIN_C7,bits=8,parity=N,BRGH1OK,ERRORS)
#byte LATC = 0x0F8B
#byte LATD = 0x0F8C
#byte LATE = 0x0F8D
#byte RCSTA = 0x0FAB
#bit OERR = RCSTA.1
#bit CREN = RCSTA.4
in the main
setup_adc_ports(AN0);
setup_adc(ADC_CLOCK_INTERNAL);
setup_psp(PSP_DISABLED);
setup_wdt(WDT_OFF);
setup_timer_0(RTCC_INTERNAL);
setup_timer_2(T2_DIV_BY_16,195,16);
setup_timer_1(T1_DISABLED);
setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
setup_low_volt_detect(FALSE);
set_tris_a(0xff);
set_tris_b(0xff);
set_tris_c(0xbc);
set_tris_d(0x81);
set_tris_e(0x06);
init_ext_eeprom();
// write_inmem_168(MCU_INITIALS_ADDR,0xff);
internal_mem_init();
disable_interrupts(GLOBAL);
enable_interrupts(INT_RDA);
enable_interrupts(INT_TIMER2);
enable_interrupts(INT_RB);
enable_interrupts(INT_EXT1);
//enable_interrupts(INT_EXT);
enable_interrupts(GLOBAL);
GPSLOCKPIN=TRUE; |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Fri Jun 13, 2008 11:33 am |
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just some notes..
I went from 18F452 to 18F4525 with no problems.
I use defines
| Code: | #bit CREN =0XFAB.4
#bit OERR =0XFAB.1
#byte RCREG=0XFAE
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karth
Joined: 10 Sep 2003
Posts: 29
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| Posted: Fri Jun 13, 2008 1:45 pm |
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can you copy the eusart portion of your code
thanks |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Mon Jun 16, 2008 8:17 am |
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sure: this is for compiler 3.249
also see
C:\Program Files\PICC\Drivers\RS485.C
C:\Program Files\PICC\Examples\EX_SISR.C
note that timer1 counts is reset when we RX a byte. Then when not receiving data counts down and indicates an idle bus.
| Code: |
//"startup code " disable rda till we are ready
disable_interrupts(INT_RDA);//disable RX
//==============================
//=====================RS485_init======================//
//Setup for RS485 communications
//init must be run before anything else
void RS485_init(void)
{
setup_timer_1(T1_INTERNAL | T1_DIV_BY_1);
set_timer1(Timer1_Initial_Value);
enable_interrupts(INT_TIMER1);//this timer waits for an idle bus
//we wait for idle bus to know that we start reading com in the right place
CREN = 0;
CREN = 1; //clear overflow error if something snuck in
enable_interrupts(INT_RDA);
if (!idle_bus)//wait for buss to go idle. Then start reading pkt's
{
restart_wdt();
}
}
//========================
//=====================tx_buffer======================//
//For transmitting data via USART and using interrupts
//must have #INT_TBE defined
void tx_buffer(char *data,int8 size)
{
int8 x;
disable_interrupts(INT_TBE); //so as not to change indx_i in 2 places, isr and here
for (x=0;x<size;x++,data++)
{
//chksum=chksum+*data;
TX_BUF[tx_indx_i] = *data;
tx_indx_i++; //increment the index
//tx_indx_i &= TXMASK; //not needed its an int8
if(tx_indx_o==tx_indx_i) //if the indexs match we are full
{
bit_set(ERRORS,1);//set error flag bit 1 for tx overflow
//disable_interrupts(INT_TBE);
//tx_indx_o++;
//tx_indx_o &= TXMASK; //not needed its an int8
}
}
enable_interrupts(INT_TBE);
return;
}
//=======================TXisr============================//
//Takes data from buffer and puts it into a TX stream (RS485)
//uses interrupts to empty buffer at proper rate
#INT_TBE
void TXisr(void)
{
CREN = 0;
idle_bus=FALSE;
fputc(TX_BUF[tx_indx_o],RS485);
tx_indx_o++; //not used//tx_indx_o &= TXMASK;
if(tx_indx_o==tx_indx_i)
{
disable_interrupts(INT_TBE);
CREN = 1;
}
}
//=======================RXisr============================//
//Takes RX data from a stream and puts it into a buffer via interrupts
#INT_RDA
void RXisr(void)
{
idle_bus=FALSE;
set_timer1(Timer1_Initial_Value);
RX_BUF[rx_indx]=RCREG;
rx_indx++;
if (rx_indx==MAXHEADER+MAXDATA+1) // check for buffer overflow
{
bit_set(ERRORS,2);//set error flag bit 2 for RXbuffer overflow
}
if (OERR)
{
bit_set(ERRORS,0);//set error flag bit 0 for USART overflow
CREN = 0;
CREN = 1;
}
}
//=======================checksum============================//
int8 chksum(char *data,int8 size)
{
int8 x;
int8 chksum=0;
for (x=0;x<size;x++,data++)
{
chksum=chksum+*data;
//fprintf(DEBUG,".");
}
return(chksum);
}
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karth
Joined: 10 Sep 2003
Posts: 29
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| Posted: Mon Jun 16, 2008 1:27 pm |
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| i am using Asynchronous mode and the compiler i am using is 3.236 is that compatible with pic18lf4525??? |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Tue Jun 17, 2008 8:03 am |
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It could be the compiler version, or something to do with the "LF" version
of the chip. |
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Charlie U
Joined: 09 Sep 2003
Posts: 183
Location: Somewhere under water in the Great Lakes
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| Posted: Tue Jun 17, 2008 12:21 pm |
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| Check the specs for the part that you are using. Look at figure 26-3 in the latest data sheet. There is a formula for max operating frequency vs supply voltage. If I am not mistaken, using this formula, the max operating frequency is 18.9MHz at 3.4v. If you are making a one off project, you might get lucky and get away with this. If this is a commercial product, you might consider some changes. |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Tue Jun 17, 2008 2:33 pm |
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| I never caught that he was running at that low of a voltage. Good catch. |
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karth
Joined: 10 Sep 2003
Posts: 29
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| Posted: Wed Jun 18, 2008 7:59 am |
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| i spoke to microchip, for 3.5 v 20mhz rock is fine.... |
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