Need help with problem turning on UART1-7

Osman Eralp

Other Parts Discussed in Thread: TM4C123GH6PM

I tried to modify the uart_echo example to use UART2. However, nothing comes out on UART2. I verified this with an oscilloscope. In fact, none of the UARTs work except UART0 which does work. I read in another post that I need to turn on the gated clocks to the UARTs by writing to the RCGCUART register at 0x400fe618, but that didn't help. I also changed the interrupt table in startup_rvmdk.S to handle an interrupt on UART2. According to the debugger, the code gets to the while loop at the end, which means it's not off in the weeds somewhere.

The relevant portion of my code is shown below. Can anyone please help? TIA.

...

// set RCGCUART
volatile uint32_t value=0;
value = (*((volatile uint32_t *)0x400FE618));
(*((volatile uint32_t *)0x400FE618)) = 0x000f;
value = (*((volatile uint32_t *)0x400FE618));

//
// Enable the peripherals used by this example.
//
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART2);

//
// Enable processor interrupts.
//
ROM_IntMasterEnable();

//
// Set GPIO A0 and A1 as UART pins.
//
ROM_GPIOPinTypeUART(GPIO_PORTD_BASE, GPIO_PIN_6);
ROM_GPIOPinTypeUART(GPIO_PORTD_BASE, GPIO_PIN_7);

//
// Configure the UART for 115,200, 8-N-1 operation.
//
ROM_UARTConfigSetExpClk(UART2_BASE, ROM_SysCtlClockGet(), 115200,
(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
UART_CONFIG_PAR_NONE));

//
// Enable the UART interrupt.
//
ROM_IntEnable(INT_UART2);
ROM_UARTIntEnable(UART2_BASE, UART_INT_RX | UART_INT_RT);

//
// Prompt for text to be entered.
//
UARTSend((uint8_t *)"Enter text: ", 12);

//
// Loop forever echoing data through the UART.
//
while(1)
{
}

...

over 12 years ago

0 Amit Ashara over 12 years ago

TI__Guru**** 244510 points

Hi Osman,

First of all I would need information on which TM4C device are you using.

Secondly, if it is TM4C123 then PD7 which is UART2_TX Pin, is a locked pin. You will have to unlock the Pin and then should be able to configure it for UART2 TX Pin.

Also for the remaining UARTs can you please send the value of the PPUART register at 0x400FE318 address. This should be useful.

Amit

0 Osman Eralp over 12 years ago in reply to Amit Ashara

Prodigy 100 points

Amit, your comment about the locked pins lead me to a solution. I am using the TM4C123 evaluation kit. I generated code using the Pin Mux utility, and saw these two lines in the output code:

HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x80;

I added them to my code, and now UART2 works! Thanks for pointing me in the right direction.

Osman

0 Amit Ashara over 12 years ago in reply to Osman Eralp

TI__Guru**** 244510 points

Hi Osman,

You did mention that UART1-7 were also not working. Any update on the same?

Amit

0 Osman Eralp over 12 years ago in reply to Amit Ashara

Prodigy 100 points

Yes, the UARTs now work. I tested UART2 on PORTD and UART3 on PORTC. Both work. The key was to unlock the pins. The clock gating had nothing to do with the problem.

0 cb1_mobile over 12 years ago in reply to Osman Eralp

Guru 117855 points

Osman Eralp said:

HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x80;

I added them to my code, and now UART2 works!

Should that prove the case - it is not due to any attempt to, "unlock" PC7 (represented by your code block, quoted above) - which has never appeared in need of any such unlock assistance... (PD7 more "welcomes" such escape from NMI)

And - as others have suggested - the single/proper "unlock" of PD7 should have had no effect upon the UART behavior of multiple, other UART Ports - which you represent now as, "working." Proper correction descriptions (but for PD7) are nowhere, "in evidence," thus others visiting here receive minimal benefit...

0 Osman Eralp over 12 years ago in reply to Osman Eralp

Prodigy 100 points

Osman Eralp said:

HWREG(GPIO_PORTC_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
HWREG(GPIO_PORTC_BASE + GPIO_O_CR) = 0x80;

I added them to my code, and now UART2 works!

Sorry, I meant to say that UART3 works. UART2 is on PORTD, which is not affected by the unlock commands above. I was testing so many UARTs I got them mixed up!

Thanks again to Amit for pointing out that the port pins need to be unlocked.

0 cb1_mobile over 12 years ago in reply to Osman Eralp

Guru 117855 points

No one seeks sorrow - new visitors would likely be confounded by that unneeded, PC7 "exercise."

Earlier you listed multiple UARTs as being DOA. (i.e. dead) Might you provide some detail as to how you restored all of those not "rescued" by the unlocking of PD7? Surely others visiting here would benefit...

And - that unlocking procedure (PD7 & PF0) was first listed here - several years back (repeatedly) by this reporter... Forum search reveals...

0 Igor Chudakov2 over 12 years ago in reply to cb1_mobile

Intellectual 870 points

For using assignments there are two headers should be included

#include "inc/hw_types.h"
#include "inc/hw_gpio.h"

HWREG(GPIO_PORTD_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
HWREG(GPIO_PORTD_BASE + GPIO_O_CR) = 0x80;

When I included these strings I also got UART2 port working with using PD7. For testing purposes I loop invitation without any interrupts. Interrupts are disabled. However, it works only if the code downloaded right after the uart_echo example. If I take power off and switch it on again the code is not working. The Uart_echo works without any problem whether I download it again or just powering it up. I check the TX pin with a scope.

Let me know if you need to look the code.

0 Markel Robregado over 12 years ago in reply to Igor Chudakov2

Guru 86865 points

Hi Igor,

You can do a search in the forum for PD7 unlocking code. This have been discussed here several times already.

-kel

0 Arunabha Deb over 12 years ago in reply to Amit Ashara

Intellectual 710 points

Hi Amit

I am working with tm4c123gh6pm 's uart module.I am just trying to send some data to my hyperterminal.My code is working fine for UART0 module.But while i want to use other uart modules i am not getting any data on my hyper terminal.As you suggested I have unlocked the pin also for particular Uart.Still it is not working.I am posting my code below.I am using ccs v5Please.help me out here.

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "inc/hw_types.h"
#include "inc/hw_gpio.h"

//*****************************************************************************

//
//*****************************************************************************
int
main(void)
{
char cThisChar;

//
HWREG(GPIO_PORTB_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
HWREG(GPIO_PORTB_BASE + GPIO_O_CR) =GPIO_PIN_1;
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
/*
//HWREG(GPIO_PORTB_BASE + GPIO_O_PCTL) = 0x00;
HWREG(GPIO_PORTB_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
HWREG(GPIO_PORTB_BASE + GPIO_O_CR) = GPIO_PIN_1;
//HWREG(GPIO_PORTB_BASE + GPIO_O_AFSEL) &= ~GPIO_PIN_1; // Alt Funct Select
HWREG(GPIO_PORTB_BASE + GPIO_O_DEN) |= GPIO_PIN_1; // Digital Enable
//HWREG(GPIO_PORTB_BASE + GPIO_O_LOCK) = 0;

SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);

//
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);

//GPIOPinConfigure(GPIO_PA0_U0RX);
GPIOPinConfigure(GPIO_PB1_U1TX);

// GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
GPIOPinTypeUART(GPIO_PORTB_BASE, GPIO_PIN_1);

//
// UARTClockSourceSet(UART1_BASE, UART_CLOCK_PIOSC);
UARTConfigSetExpClk(UART1_BASE, SysCtlClockGet(), 115200,
(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
UART_CONFIG_PAR_NONE));

UARTCharPut(UART1_BASE, 'n');

while(1);
return(0);
}

Thanks and regards

Arun

0 Amit Ashara over 12 years ago in reply to Arunabha Deb

TI__Guru**** 244510 points

Hello Arun,

Are you using the DK or EK boards or a custom board?

Regards

Amit

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Need help with problem turning on UART1-7