Shaan NagyAustin HushowerRay William
Published

HarRay POTentiomeTER and the Half-Heard Piezo

We are innovating the world of sound engineering. Using cutting edge technology, we bring you a buzzer whose frequency is keyed to a dial.

BeginnerWork in progress252
HarRay POTentiomeTER and the Half-Heard Piezo

Things used in this project

Hardware components

EK-TM4C123GXL TM4C Tiva LaunchPad
Texas Instruments EK-TM4C123GXL TM4C Tiva LaunchPad
×1
Seeed Sidekick Basic Kit for TI Launchpad
×1
Buzzer, Piezo
Buzzer, Piezo
×1
Potentiometer - 10K Ohm with Knob
×1
Tilt Switch, SPST
Tilt Switch, SPST
×1

Software apps and online services

Code Composer Studio
Texas Instruments Code Composer Studio

Story

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Schematics

Fritzthing File

Fritzing Block Diagram

This diagram demonstrates our product's configuration of components and wires on the breadboard.

Code

main.c

C/C++
Runs project.
/*
 * main.c
 *
 * This is the configuration we will use:
 * 		+ 	Our input pin will be PE4.
 *			Not used as a GPIO, but using its Alternate Function
 *		+	There are two ADC modules.  We will use ADC0.
 *		+	We will configure it for a sample rate of 125 kHz.
 *		+	We will start sampling via software and poll to determine when data is ready.
 *			This will be how we synchronize the CPU with ADC0.
 *
 * 	This example will follow the configuration used by Valvano in section 10.4.1 TM4C ADC details
 *
 * Date 27 March 2016
 */

#include "ADC0_registers.h"

extern void System_Clock_Init(void);
extern void ADC0_InitSWTriggerSeq3_PE4(void);
extern unsigned int ADC0_Sample_Seq3(void);

int main(void) {

        int sample_ADC0;
        float sample_voltage;
        float potresistance;

        int i;

        System_Clock_Init();

        // Nice function that sets up the ADC for us. :)
        ADC0_InitSWTriggerSeq3_PE4();

        // Set up the pointers to all of our registers.
        unsigned int volatile *pRCGCGPIO = (unsigned int *) (0x400FE000 + 0x608);
        unsigned int volatile *pGPIOLOCK_PortF = (unsigned int *)(0x40025000 + 0x520);
        unsigned int volatile *pGPIOCR_PortF = (unsigned int *)(0x40025000 + 0x524);
        unsigned int volatile *pGPIODIR_PortF = (unsigned int *) (0x40025000 + 0x400);
        unsigned int volatile *pGPIOAFSEL_PortF = (unsigned int *) (0x40025000 + 0x420);
        unsigned int volatile *pGPIODEN_PortF = (unsigned int *) (0x40025000 + 0x51C);
        unsigned int volatile *pGPIODATA_PortF = (unsigned int *) (0x40025000 + 0x3FC);

        // Set up Port F
        *pRCGCGPIO = *pRCGCGPIO | 0x0020;
        while ( (*pRCGCGPIO & 0x0020) == 0 );

        *pGPIOLOCK_PortF        = 0x4C4F434B;
        *pGPIOCR_PortF = *pGPIOCR_PortF | 0x1F;

        // SET UP PIN 3 for the speaker.
        *pGPIODIR_PortF = *pGPIODIR_PortF | 0x08;  // 0x08 looks familiar. This would SET a 1 (because of the OR) on the 3rd bit of the register. This sets Pin F3 to be an output.
        *pGPIOAFSEL_PortF = *pGPIOAFSEL_PortF & ~0x08; // No alternative functions for this pin
        *pGPIODEN_PortF = *pGPIODEN_PortF | 0x08; // Digital enable the pin

        while(1)
        {
                // Determine the voltage through R1 in our potentiometer
                sample_ADC0 = ADC0_Sample_Seq3();
                sample_voltage = (3.3/4095.0) * (float) sample_ADC0;

                // What is the resistance of the R1 in potentiometer? V_meas/3.3 = R1/(R1+R2)= R1/10,000.
                potresistance = 10000 * (sample_voltage/3.3);

                //Do a square wave! (Turn on the pin, wait, turn off the pin, wait (Pin F3 (like we did with the blinking of the LED)))

                // Delay for a bit. Potresistance determines how long we hold each crest and trough, and this determines the frequency for a square wave. 
                for(i = 0; i < (int) (potresistance); i++) {}

                // Toggle sound.
                *pGPIODATA_PortF = *pGPIODATA_PortF ^ 0x08;
        }
        return 0;
}

ADC0_InitSWTriggerSeq3_PE4.c

C/C++
Sets up ADC module.
/*
 * ADC0_InitSWTriggerSeq3_PE4.c
 *
 *  Created on: Mar 28, 2016
 *      Author: Ray
 */

#include "ADC0_registers.h"


void
ADC0_InitSWTriggerSeq3_PE4( void )
{
	/*
	 * Now step through the steps for setting up the ADC module.
	 */

	// Steps 1 - 5 follow that in Valvano Sec 10.4.1

	// Step 6a: Enable the ADC clock for ADC0 by setting bit 0 of the RCGCADC register
	*pRCGCADC |= 0x0001;	// DS p 352

	// Step 1a: Turn on the clocks for port E.
	//	Note:	port E clocks are controlled by bit 4 (R4) of *pRCGCGPIO.
	//			In _binary_ this would correspond to a mask of 0b01.0000.
	//			In _hex_ this would correspond to a mask of 0x10
	*pRCGCGPIO |= 0x0010;	// DS p 340

	// Step 1b: Check to be sure the clocks have started.
	//			This can take a few clock cycles.
	//			Keep checking bit 4 until it is no longer 0.

	while((*pPRGPIO & 0x10) != 0x10){}	// DS p 406

	// Let's use PE4 as the analog input to ADC0.

	// Step 2:  Set the direction of the pin to be used.  The pins
	//			can be configured as either input or output.
	//			In _binary_ the bit position mask would correspond to a mask of 0b1.0000
	//			In _hex_ this would correspond ot a mask of 0x10;
	//			To make PE4 an input, we must clear this bit.  Thus:
	*pGPIODIR_PortE &= ~0x0010;	// DS p 663

	// Step 3: 	Enable the Alternate Function on pin PE4.
	//			This means we set the bit corresponding to PE4.
	*pGPIOAFSEL_PortE |= 0x0010;	// DS p 672

	// Step 4:	Disable the digital function on pin PE4.
	//			This means we clear the bit corresponding to PE4.
	*pGPIODEN_PortE &= ~0x0010;	// DS p 682

	// Step 5:	Enable the analog function on pin PE4.
	//			This means we set the bit corresponding to PE4.
	*pGPIOAMSEL_PortE |= 0x0010;	// DS p 687

	// Completed configuring PE4 for use as an analog input

	// Step 6:14  configure ADC0.

	while ((*pPRADC & 0x01) != 0x01){}	// Wait for the ADC0 to be ready.

	// Step 7: Specify the number of ADC conversions per second.  This value corresponds to 125 ksps
	*pADCPC_ADC0 = 0x0001;	// DS p 892

	// Step 8: Set the priorities of each of the four sequencers.  We set sample sequencer 3 as the highest
	// prioirity and set the others with lower, unique priorities.
	*pADCSSPRI_ADC0 = 0x0123;	// DS p 842

	// Step 9: Ensure that the sample sequencer 3 is disabled by clearing the corresponding ASEN3
	// bit (bit 3) in the ADCACTSS  register.
	*pADCACTSS_ADC0 &= ~0x0008;	// DS p 822

	// Step 10: Select the event that initiates sampling for sample sequencer 3.  Configure the
	// 'trigger event' to be initiated by the processor setting the SSn bit in the ADCPSSI register.
	*pADCEMUX_ADC0 &= 0x0FFF;	// DS p 834

	// Step 11:  For each sample in the sample sequence, configure the corresponding input source in the
	// ADCSSMUXn register.  For our case we sample channel AIN9, which is PE4.  This is shown in Table 13-1 on
	// page 802.  We clear the SS3 field and set channel to AIN9.
	*pADCSSMUX3_ADC0 = (*pADCSSMUX3_ADC0 & 0XFFFFFFFF0) + 0X9;	// DS p 876

	// Step 12: For each sample in the sample sequence, configure the sample control bits in the
	// corresponding nibble in the ADCSSCTL3  register.  Our setting is:
	// TS0 = 0, IE0 = 1, END0 = 1,  D0 = 0 or, the nibble is 0b0110 = 6
	// This is the register to use to pick temperature sampling.

	*pADCSSCTL3_ADC0 = 0x0006;	// DS p 877

	// Step 13:  If interrupts are to be used, set the corresponding MASK bit in the ADCIM  register.
	// With software start, we do not want ADC interrupts, so we clear bit 3.
	*pADCIM_ADC0 &= ~0x0008;		// DS p 826

	// Step 14:	Enable the sample sequencer logic by setting the corresponding ASENn  bit in the
	// ADCACTSS register.  To enable sequencer 3, we write a 1 to bit 3 (ASEN3).

	*pADCACTSS_ADC0 |= 0x0008;	// DS p 822

	// Done with the initialization of the ADC.  Time to do some converting!

	// This is a busy-wait or polling based approach to talking to a typically slow peripheral.  In this case,
	// the peripheral happens to be the ADC we have set up.  0 to 3.3V maps to the sample ranges of
	// 0 to 4095 (2^12 - 1)

	// Do a battery test using PE4...
	// Then do a version using the temperature probe...

}

ADC0_registers.c

C/C++
Set pointers to necessary ADC registers.
/*
 * ADC0_registers.c
 *
 *  Created on: Mar 28, 2016
 *      Author: Ray
 */

#include "ADC0_registers.h"

	/*
	 * First define the pointers to the key registers needed for configuring the PLL
	 */

	// pRCC2 is a pointer to the Run-Mode Clock Configuration 2 Register (DS p 260)
	unsigned int volatile *pRCC2 = (unsigned int *) (0x400FE000 + 0x070);

	// pRIS is a pointer to the Raw Interrupt Status Register (DS p244)
	unsigned int volatile *pRIS = (unsigned int *) (0x400FE000 + 0x050);

	/*
	 * Next, define the pointers to the key registers needed for configuring
	 * PE4 as an analog input.  Note that the use of volatile ensures that
	 * the compiler always carries out the memory accesses, rather than optimizing
	 * them out (for example, if the access is in a loop).
	 */

	// pRCGCGPIO is a pointer to the General-Purpose Input/Output Run Mode Clock Gating Control Register (DS p 340)
	unsigned int volatile *pRCGCGPIO = (unsigned int *) (0x400FE000 + 0x608);

	// pPRGPIO is a pointer to the General-Purpose Input/Output Peripheral Ready Register (DS p 406)
	unsigned int volatile *pPRGPIO = (unsigned int *) (0x400FE000 + 0xA08);

	// pGPIODIR_PortE is a pointer to the GPIO Direction register for port E on the APB bus (DS p 663)
	unsigned int volatile *pGPIODIR_PortE = (unsigned int *) (0x40024000 + 0x400);

	// pGPIOAFSEL_PortE is a pointer to the GPIO Alternate Function Select register for port E on the APB bus (DS p 672)
	unsigned int volatile *pGPIOAFSEL_PortE = (unsigned int *) (0x40024000 + 0x420);

	// pGPIODEN_PortE is a pointer to the GPIO Digital Enable register for port E on the APB bus (DS p 682)
	unsigned int volatile *pGPIODEN_PortE = (unsigned int *) (0x40024000 + 0x51C);

	// pGPIOAMSEL_PortE is a pointer to the GPIO Analog Mode Select register for port E on the APB bus (DS p 687)
	unsigned int volatile *pGPIOAMSEL_PortE = (unsigned int *) (0x40024000 + 0x528);

	/*
	 * Now define the memory mapped register addresses needed to configure A to D converter ADC0
	 */

	// pRCGCADC is a pointer to the Analog-to-Digital Converter Run Mode Clock Gating Control Register (DS p 352)
	unsigned int volatile *pRCGCADC = (unsigned int *) (0x400FE000 + 0x638);

	// pADCPC_ADC0 is a pointer to the ADC Peripheral Configuration Register for ADC0 (DS p 892)
	unsigned int volatile *pADCPC_ADC0 = (unsigned int *) (0x40038000 + 0xFC4);

	// pADCPCSSPRI_ADC0 is a pointer to the Sample Sequencer Priority Register for ADC0 (DS p 842)
	unsigned int volatile *pADCSSPRI_ADC0 = (unsigned int *) (0x40038000 + 0x020);

	// pADCACTSS_ADC0 is a pointer to the ADC Active Sample Sequencer Register for ADC0 (DS p 822)
	unsigned int volatile *pADCACTSS_ADC0 = (unsigned int *) (0x40038000 + 0x0);

	// pADCEMUX_ADC0 is a pointer to the ADC Event Multiplexer Select Register for ADC0 (DS p 834)
	unsigned int volatile *pADCEMUX_ADC0 = (unsigned int *) (0x40038000 + 0x014);

	// pADCSSMUX3_ADC0 is a pointer to the ADC Sample Sequence Input Multiplexer Select 3 Register for ADC0 (DS p 876)
	unsigned int volatile *pADCSSMUX3_ADC0 = (unsigned int *) (0x40038000 + 0x0A0);

	// pADCSSCTL3_ADC0 is a pointer to the ADC Sample Sequence Control 3 Register for ADC0 (DS p 877)
	unsigned int volatile *pADCSSCTL3_ADC0 = (unsigned int *) (0x40038000 + 0x0A4);

	// pADCIM_ADC0 is a pointer to the ADC Interrupt Mask3 Register for ADC0 (DS p 826)
	unsigned int volatile *pADCIM_ADC0 = (unsigned int *) (0x40038000 + 0x08);

	// pADCPSSI_ADC0 is a pointer to the ADC Processor Sample Sequence Initiate Register for ADC0 (DS p 846)
	unsigned int volatile *pADCPSSI_ADC0 = (unsigned int *) (0x40038000 + 0x028);

	// pADCRIS_ADC0 is a pointer to the ADC Raw Interrupt Status Register for ADC0 (DS p 824)
	unsigned int volatile *pADCRIS_ADC0 = (unsigned int *) (0x40038000 + 0x04);

	// pADCSSFIFO3_ADC0 is a pointer to the ADC Sample Sequence Result FIFO 3 Register for ADC0 (DS p 861)
	unsigned int volatile *pADCSSFIFO3_ADC0 = (unsigned int *) (0x40038000 + 0x0A8);

	// pADCISC_ADC0 is a pointer to the ADC Interrupt Status and Clear Register for ADC0 (DS p 829)
	unsigned int volatile *pADCISC_ADC0 = (unsigned int *) (0x40038000 + 0x00C);

	// pPRADC is a pointer to the Analog-to-Digital Converter Peripheral Ready Register (DS p 418)
	unsigned int volatile *pPRADC = (unsigned int *) (0x400FE000 + 0xA38);

ADC0_registers.h

C Header File
Define pointers for necessary ADC registers.
/*
 * ADC0_registers.h
 *
 *  Created on: Mar 28, 2016
 *      Author: Ray
 */

#ifndef ADC0_REGISTERS_H_
#define ADC0_REGISTERS_H_

	/*
	 * First define the pointers to the key registers needed for configuring the PLL
	 */

	// pRCC2 is a pointer to the Run-Mode Clock Configuration 2 Register (DS p 260)
	extern unsigned int volatile *pRCC2;

	// pRIS is a pointer to the Raw Interrupt Status Register (DS p244)
	extern unsigned int volatile *pRIS;

	/*
	 * Next, define the pointers to the key registers needed for configuring
	 * PE4 as an analog input.  Note that the use of volatile ensures that
	 * the compiler always carries out the memory accesses, rather than optimizing
	 * them out (for example, if the access is in a loop).
	 */

	// pRCGCGPIO is a pointer to the General-Purpose Input/Output Run Mode Clock Gating Control Register (DS p 340)
	extern unsigned int volatile *pRCGCGPIO;

	// pPRGPIO is a pointer to the General-Purpose Input/Output Peripheral Ready Register (DS p 406)
	extern unsigned int volatile *pPRGPIO;

	// pGPIODIR_PortE is a pointer to the GPIO Direction register for port E on the APB bus (DS p 663)
	extern unsigned int volatile *pGPIODIR_PortE;

	// pGPIOAFSEL_PortE is a pointer to the GPIO Alternate Function Select register for port E on the APB bus (DS p 672)
	extern unsigned int volatile *pGPIOAFSEL_PortE;

	// pGPIODEN_PortE is a pointer to the GPIO Digital Enable register for port E on the APB bus (DS p 682)
	extern unsigned int volatile *pGPIODEN_PortE;

	// pGPIOAMSEL_PortE is a pointer to the GPIO Analog Mode Select register for port E on the APB bus (DS p 687)
	extern unsigned int volatile *pGPIOAMSEL_PortE;

	/*
	 * Now define the memory mapped register addresses needed to configure A to D converter ADC0
	 */

	// pRCGCADC is a pointer to the Analog-to-Digital Converter Run Mode Clock Gating Control Register (DS p 352)
	extern unsigned int volatile *pRCGCADC;

	// pADCPC_ADC0 is a pointer to the ADC Peripheral Configuration Register for ADC0 (DS p 892)
	extern unsigned int volatile *pADCPC_ADC0;

	// pADCPCSSPRI_ADC0 is a pointer to the Sample Sequencer Priority Register for ADC0 (DS p 842)
	extern unsigned int volatile *pADCSSPRI_ADC0;

	// pADCACTSS_ADC0 is a pointer to the ADC Active Sample Sequencer Register for ADC0 (DS p 822)
	extern unsigned int volatile *pADCACTSS_ADC0;

	// pADCEMUX_ADC0 is a pointer to the ADC Event Multiplexer Select Register for ADC0 (DS p 834)
	extern unsigned int volatile *pADCEMUX_ADC0;

	// pADCSSMUX3_ADC0 is a pointer to the ADC Sample Sequence Input Multiplexer Select 3 Register for ADC0 (DS p 876)
	extern unsigned int volatile *pADCSSMUX3_ADC0;

	// pADCSSCTL3_ADC0 is a pointer to the ADC Sample Sequence Control 3 Register for ADC0 (DS p 877)
	extern unsigned int volatile *pADCSSCTL3_ADC0;

	// pADCIM_ADC0 is a pointer to the ADC Interrupt Mask3 Register for ADC0 (DS p 826)
	extern unsigned int volatile *pADCIM_ADC0;

	// pADCPSSI_ADC0 is a pointer to the ADC Processor Sample Sequence Initiate Register for ADC0 (DS p 846)
	extern unsigned int volatile *pADCPSSI_ADC0;

	// pADCRIS_ADC0 is a pointer to the ADC Raw Interrupt Status Register for ADC0 (DS p 824)
	extern unsigned int volatile *pADCRIS_ADC0;

	// pADCSSFIFO3_ADC0 is a pointer to the ADC Sample Sequence Result FIFO 3 Register for ADC0 (DS p 861)
	extern unsigned int volatile *pADCSSFIFO3_ADC0;

	// pADCISC_ADC0 is a pointer to the ADC Interrupt Status and Clear Register for ADC0 (DS p 829)
	extern unsigned int volatile *pADCISC_ADC0;

	// pPRADC is a pointer to the Analog-to-Digital Converter Peripheral Ready Register (DS p 418)
	extern unsigned int volatile *pPRADC;

#endif /* ADC0_REGISTERS_H_ */

System_Clock_Init.c

C/C++
Handles initialization of the system level clocks.
/*
 * System_Clock_init.c
 *
 *  Created on: Mar 28, 2016
 *      Author: Ray
 */

// Handles initialization of the system level clocks.

#include "ADC0_registers.h"

void
System_Clock_Init(void)
{
	/*
	 * In order for the ADC module to be used, the PLL must be enabled and programmed to a supported
	 * crystal frequency in the RCC register (see page 260).  We will use the example found in Valvano
	 * Sec. 4.3
	 *
	 * Our processor on the LaunchPad had a 16 MHz main oscillaor and we enable it to run at 80 MHz.
	 */

	// Step 1: enable the use of the RCC2 register fields.
	*pRCC2 |= 0x80000000;	//	DS p 260

	// Step 2:
	*pRCC2 |= 0x00000800;	// 1) bypass PLL while initializing

	// Step 3: Select the crystal value and oscillator source
	*pRCC2 = (*pRCC2 & ~0x000007C0)	// Clear bits 10-6
			+ 0x00000540;			// 10101, configure for 16 MHz crystal
	*pRCC2 &= ~0x00000070;	// Configure for main oscillator sources

	// Step 4: Activate PLL by clearing PWRDN
	*pRCC2 &= ~0x00002000;

	// Step 5: Set the desired system divider
	*pRCC2 |= 0x40000000;	// use 400 MHz PLL
	*pRCC2 = (*pRCC2 & ~0x1FC00000) + (4 << 22);	// 80 MHz

	while ((*pRIS & 0x00000040) == 0){}

	// Step 6: Enable use of PLL by clearing BYPASS
	*pRCC2 &= ~0x00000300;

	// Done enabling the PLL.
}

ADC0_Sample_Seq3.c

C/C++
Procedure for getting ADC value.
/*
 * ADC0_Sample_Seq3.c
 *
 *  Created on: Mar 28, 2016
 *      Author: Ray
 */

#include "ADC0_registers.h"

unsigned int
ADC0_Sample_Seq3(void)

{
	unsigned int sample_ADC0;

	// Step 1:  Start collecting a single sample by writing a 1 to bit 3 of the ADCPSSI register.
	*pADCPSSI_ADC0 = 0x08;	// DS p 846

	// Step 2: Wait for the conversion of the single sample we have requested.  Bit 3 will be set when
	// a sample has completed conversion. DS p 824
	while ((*pADCRIS_ADC0 & 0x08) == 0){};

	// Step 3: Now that conversion is complete, read the 12-bit digital sample from the FIFO for
	// Sample Sequencer 3, the ADCSSFIFO3 register!!!
	sample_ADC0 = *pADCSSFIFO3_ADC0 & 0x0FFF; // DS p 861

	// Step 4: Acknowledge the we have complete the read.  This will allow for the system to
	// return to the state where it can process another sample, when requested.  (DS p 829)

	*pADCISC_ADC0 = 0x08;

	return sample_ADC0;
}

Credits

Shaan Nagy

Shaan Nagy

1 project • 1 follower
Austin Hushower

Austin Hushower

1 project • 0 followers
Ray William

Ray William

1 project • 1 follower

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