RFM12B with MSP430 Tutorial | MSP430 Projects

Here is a quick tutorial of basic communication between two RFM12B’s driven with MSP430 Launchpads.

Last couple of days (10 days) I have been occupied with two FRM12B modules, trying to get them to communicate. I need them to make some kind of wireless temperature sensors. I had some simple weather station from Lidl, but it stopped working, so I said I will make one myself. This is the part for tranferring measuremensts from cold outside, into our warm home. I had short connection on receiver board and it took me a few days to realize that, so it took me much more than it should. Learn from my mistakes! I have an adapter board that fits on MSP-EXP430G2 Launchpad board. I also made small board to fit RFM12B on it. This is how everything fits together:

As you can see, the board was not properly drawn first time.

There are 5 connection between RFM12B and MSP430, plus two for power. They are connected as follows:

MSP430 <-> RFM12B
P1.7 <-> SDO
P1.6 <-> SDI
P1.5 <-> SCK
P1.4 <-> nSEL
P1.3 <-> nIRQ

MSP430 <-> RFM12B

P1.7 <-> SDO

P1.6 <-> SDI

P1.5 <-> SCK

P1.4 <-> nSEL

P1.3 <-> nIRQ

I use Code Composer Studio 6.2.0.00050, which is FREE, because there is version 7.x out. You can get it here. You will need to register, to be able to download software. This is link to FREE license and it’s installation instructions. I will not explain how to install it, since you must be smart enough to do it if you are programming microcontrollers.

We need to start by creating new project (Project -> New CCS Project…):

Now we need to select our microcontroller (I selected MSP430G2231 since this is the one in my launchpad):

We also need to name our project. I named this one RFM12B_TX_002. RFM12 is obvious, TX is because this is the transmiter part of our project and 002, because I already have 001 and this is how I sequnentially name all my software projects. And this is what it looks after we click finish:

I used different information sources for this. Some pdf’s from internet, some code found on random sites, some code I already used on ATMEGA8 for RFM12B, some info from forums, which didn’t help a lot, since no one else had shortcut on circuit, like I did. 🙁 But finally it worked and here is code I use to do it.

This is code for main.c:

/*
 * Created by Slemi
 * 7.3.2018
 */

#include <msp430.h>
#include "rfm12b_slemi_tx.h"

#define key_press !(P1IN & 0x08)

int main(void)
{
	uint16_t tmp;
	WDTCTL = WDTPW | WDTHOLD;	// Stop watchdog timer
	//set clock to 1MHz
	BCSCTL1 = CALBC1_1MHZ;
	DCOCTL = CALDCO_1MHZ;

	/* Clock configuration. CPU is running at ~1MHz */
	BCSCTL1 &= ~(XTS);  // Select low frequency mode for LFXT1, high frq mode not supported on MSP430G2231
	BCSCTL1 |= DIVA_3;  // ACLK = 32768Hz / 8 = 4096Hz
	BCSCTL3 &= ~(LFXT1S0 | LFXT1S1);	//32768-Hz crystal on LFXT1

	rf12_port_init();
	rf12_init();

	//wait for RFM21B to wake up
	__delay_cycles(1000000);
	_enable_interrupt();

	while(1)
	{
		rf12_write_cmd(RF_TX_ON);
		rf12_write_cmd(0x0000);
		rf12_write_data(0xAA);
		rf12_write_data(0xAA);
		rf12_write_data(0xAA);
		rf12_write_data(0x2D);
		rf12_write_data(0xD4);
		rf12_write_data(0x30);
		rf12_write_data(0x31);
		rf12_write_data(0x32);
		rf12_write_data(0x33);
		rf12_write_data(0x34);
		rf12_write_data(0x35);
		rf12_write_data(0x36);
		rf12_write_data(0x37);
		rf12_write_data(0x38);
		rf12_write_data(0x39);
		rf12_write_data(0x3A);
		rf12_write_data(0x3B);
		rf12_write_data(0x3C);
		rf12_write_data(0x3D);
		rf12_write_data(0x3E);
		rf12_write_data(0x3F);
		rf12_write_data(0x39);
		rf12_write_data(0xAA);
		rf12_write_data(0xAA);
		rf12_write_data(0xAA);
		rf12_write_cmd(RF_IDLE_MODE);
		P1OUT |= 0x01;
		_delay_cycles(100000);
		P1OUT &= 0xFE;
		_delay_cycles(1900000);
	}
	return 0;
}

void __attribute__((interrupt(PORT1_VECTOR)))
PORT1_ISR(void)
{
	if(P1IFG & BIT3)
	{
		//P1OUT |= BIT0;
	}
	P1IFG &= ~BIT3;
}

* Created by Slemi

* 7.3.2018

#include <msp430.h>

#include "rfm12b_slemi_tx.h"

#define key_press !(P1IN & 0x08)

int main(void)

{

uint16_t tmp;

WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer

//set clock to 1MHz

BCSCTL1 = CALBC1_1MHZ;

DCOCTL = CALDCO_1MHZ;

/* Clock configuration. CPU is running at ~1MHz */

BCSCTL1 &= ~(XTS); // Select low frequency mode for LFXT1, high frq mode not supported on MSP430G2231

BCSCTL1 |= DIVA_3; // ACLK = 32768Hz / 8 = 4096Hz

BCSCTL3 &= ~(LFXT1S0 | LFXT1S1); //32768-Hz crystal on LFXT1

rf12_port_init();

rf12_init();

//wait for RFM21B to wake up

__delay_cycles(1000000);

_enable_interrupt();

while(1)

{

rf12_write_cmd(RF_TX_ON);

rf12_write_cmd(0x0000);

rf12_write_data(0xAA);

rf12_write_data(0x2D);

rf12_write_data(0xD4);

rf12_write_data(0x30);

rf12_write_data(0x31);

rf12_write_data(0x32);

rf12_write_data(0x33);

rf12_write_data(0x34);

rf12_write_data(0x35);

rf12_write_data(0x36);

rf12_write_data(0x37);

rf12_write_data(0x38);

rf12_write_data(0x39);

rf12_write_data(0x3A);

rf12_write_data(0x3B);

rf12_write_data(0x3C);

rf12_write_data(0x3D);

rf12_write_data(0x3E);

rf12_write_data(0x3F);

rf12_write_data(0x39);

rf12_write_data(0xAA);

rf12_write_cmd(RF_IDLE_MODE);

P1OUT |= 0x01;

_delay_cycles(100000);

P1OUT &= 0xFE;

_delay_cycles(1900000);

}

return 0;

}

void __attribute__((interrupt(PORT1_VECTOR)))

PORT1_ISR(void)

{

if(P1IFG & BIT3)

{

//P1OUT |= BIT0;

}

P1IFG &= ~BIT3;

}

In case you try to change something, don’t forget you need to use FIFOReset();, otherwise you will get less that half the data through! Don’t ask me how I know!

We also need one other file, where the magic happens. We need to make new header file (Right click on project name -> New -> Header File):

Give it some name and click Finish (I marked wrong here, the filename should be marked):

Here is our new file opened and ready:

If you name it different you need to change include at the beginning of main.c accordingly:

Here is the code for out new file:

/*
 * Created by Slemi
 * 7.3.2018
 */

#ifndef RFM12B_SLEMI_TX_H_
#define RFM12B_SLEMI_TX_H_

#include <msp430.h>
#include <stdint.h>

#define HW_SPI

// SDI, SDO refers to msp430 device's pins, NOT RFM12B's
#define SDI     BIT7		// to SDO
#define SDO     BIT6		// to SDI
#define SCK     BIT5		// to SCK
#define SEL     BIT4		// to nSEL
#define IRQ			BIT3		// to nIRQ
#define RED_LED BIT0
#define GRN_LED BIT6

// RF12 command codesTODO change
#define RF_RX_ON  0x82DD
#define RF_TX_ON   0x823D
#define RF_IDLE_MODE    0x820D
#define RF_SLEEP_MODE   0x8205
#define RF_WAKEUP_MODE  0x8207
#define RF_TXREG_WRITE  0xB800
#define RF_RX_FIFO_READ 0xB000
#define RF_WAKEUP_TIMER 0xE000

#define izh0_on		P1OUT |= BIT0
#define izh0_off	P1OUT &= ~BIT0
#define izh1_on		P1OUT |= BIT1
#define izh1_off	P1OUT &= ~BIT1
/*#define izh2_on		P1OUT |= BIT2
 #define izh2_off	P1OUT &= ~BIT2*/

#define nSEL_LOW 	P1OUT &= ~(SEL)
#define nSEL_HIGH	P1OUT |= (SEL)
#define SDO_HIGH	P1OUT |= (SDO)
#define SDO_LOW		P1OUT &= ~(SDO)
#define SCK_HIGH	P1OUT |= (SCK)
#define SCK_LOW		P1OUT &= ~(SCK)

void rf12_port_init(void);
uint16_t rf12_write_cmd(uint16_t rf12data);
void rf12_init(void);
void rf12_write_data(uint16_t data);
void FIFOReset(void);
unsigned int rfRecv(void);
unsigned char waitForData(void);

void rf12_port_init(void)
{
	P1DIR |= SCK | SDO | SEL | RED_LED | BIT1 | BIT2;	//outputs
	P1OUT &= ~BIT2 & ~BIT1 & ~BIT0;
	P1DIR &= ~SDI & ~BIT3 & ~BIT2;	//input
	//init ports
	P1REN |= BIT7 | BIT3 | BIT2;  //Enable pull-up resistor for button/RFM12B IRQ
	P1OUT |= BIT7 | BIT3 | BIT2;  //Set input for key high for enabling detection of keypress or IRQ
	P1IFG &= ~BIT3 & ~BIT2;  //clear interrupt flag for bit3 of PORT1
	P1IE |= BIT3 | BIT2;		//enable interrupt on P1.3
#ifdef HW_SPI
	//enable SDI, SDO and SCLK, master mode, MSB first, output enabled, held in reset state
	USICTL0 = USIPE7 | USIPE6 | USIPE5 | USIMST | USIOE | USISWRST;  //TODO sw solution

	// SMCLK / 16
	USICKCTL = USIDIV_4 + USISSEL_2;		//TODO sw solution

	// clock phase
	USICTL1 |= USICKPH;		//TODO sw solution

	// USI release from reset
	USICTL0 &= ~USISWRST;		//TODO sw solution
#endif
}

#ifdef HW_SPI
uint16_t rf12_write_cmd(uint16_t data)
{
	nSEL_LOW;
	USISR = data;	//load SPI data register
	USICTL1 &= ~USIIFG;  //clear SPI interrupt
	USICNT = USI16B | 16;//select 16 bit data size and select 16 bits to be received/transmitted
	while((USICTL1 & USIIFG) != 0x01)	//wait for data transmitted interrupt
	{
	}
	nSEL_HIGH;
	return USISR;
}
#else
uint16_t rf12_write_cmd(uint16_t rf12data)
{
	uint16_t return_data = 0;
	uint8_t i;
	nSEL_LOW;
	for(i = 0; i < 15; i++)
	{
		if(rf12data & 0x8000)
		SDO_HIGH;
		else
		SDO_LOW;
		SCK_HIGH;
		if(P1IN & SDI)
		return_data++;
		return_data = return_data << 1;
		SCK_LOW;
		rf12data = rf12data << 1;
	}
	nSEL_HIGH;
	return return_data;
}
#endif

void rf12_init(void)
{
	rf12_write_cmd(0x0000);
	rf12_write_cmd(0x80E8);
	rf12_write_cmd(RF_TX_ON);
	rf12_write_cmd(0xA680);
	rf12_write_cmd(0xC647);
	rf12_write_cmd(0x94A2);
	rf12_write_cmd(0xC2AC);
	rf12_write_cmd(0xCA83);
	rf12_write_cmd(0xCED4);
	rf12_write_cmd(0xC483);
	rf12_write_cmd(0x9855);
	rf12_write_cmd(0xCC77);
	rf12_write_cmd(0xE000);
	rf12_write_cmd(0xC800);
	rf12_write_cmd(0xC049);
}

void rf12_write_data(uint16_t data)
{
	while(P1IN & BIT3)
	{
	}
	rf12_write_cmd(0xB800 + data);
}

void FIFOReset(void)
{
	rf12_write_cmd(0xCA81);
	rf12_write_cmd(0xCA83);
}

unsigned int rfRecv(void)
{
	unsigned int data;
	data = rf12_write_cmd(0xB000);
	return (data & 0x00FF);
}

unsigned char waitForData(void)
{
	SDO_LOW;
	nSEL_LOW;
	SCK_HIGH;
	if(P1IN & BIT7)
	{
		SCK_LOW;
		SDO_HIGH;
		nSEL_HIGH;
		return 1;
	}
	else
	{
		SCK_LOW;
		SDO_HIGH;
		nSEL_HIGH;
		return 0;
	}
}

#endif /* RFM12B_SLEMI_TX_H_ */

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* Created by Slemi

* 7.3.2018

#ifndef RFM12B_SLEMI_TX_H_

#define RFM12B_SLEMI_TX_H_

#include <msp430.h>

#include <stdint.h>

#define HW_SPI

// SDI, SDO refers to msp430 device's pins, NOT RFM12B's

#define SDI BIT7 // to SDO

#define SDO BIT6 // to SDI

#define SCK BIT5 // to SCK

#define SEL BIT4 // to nSEL

#define IRQ BIT3 // to nIRQ

#define RED_LED BIT0

#define GRN_LED BIT6

// RF12 command codesTODO change

#define RF_RX_ON 0x82DD

#define RF_TX_ON 0x823D

#define RF_IDLE_MODE 0x820D

#define RF_SLEEP_MODE 0x8205

#define RF_WAKEUP_MODE 0x8207

#define RF_TXREG_WRITE 0xB800

#define RF_RX_FIFO_READ 0xB000

#define RF_WAKEUP_TIMER 0xE000

#define izh0_on P1OUT |= BIT0

#define izh0_off P1OUT &= ~BIT0

#define izh1_on P1OUT |= BIT1

#define izh1_off P1OUT &= ~BIT1

/*#define izh2_on P1OUT |= BIT2

#define izh2_off P1OUT &= ~BIT2*/

#define nSEL_LOW P1OUT &= ~(SEL)

#define nSEL_HIGH P1OUT |= (SEL)

#define SDO_HIGH P1OUT |= (SDO)

#define SDO_LOW P1OUT &= ~(SDO)

#define SCK_HIGH P1OUT |= (SCK)

#define SCK_LOW P1OUT &= ~(SCK)

void rf12_port_init(void);

uint16_t rf12_write_cmd(uint16_t rf12data);

void rf12_init(void);

void rf12_write_data(uint16_t data);

void FIFOReset(void);

unsigned int rfRecv(void);

unsigned char waitForData(void);

void rf12_port_init(void)

{

P1DIR |= SCK | SDO | SEL | RED_LED | BIT1 | BIT2; //outputs

P1OUT &= ~BIT2 & ~BIT1 & ~BIT0;

P1DIR &= ~SDI & ~BIT3 & ~BIT2; //input

//init ports

P1REN |= BIT7 | BIT3 | BIT2; //Enable pull-up resistor for button/RFM12B IRQ

P1OUT |= BIT7 | BIT3 | BIT2; //Set input for key high for enabling detection of keypress or IRQ

P1IFG &= ~BIT3 & ~BIT2; //clear interrupt flag for bit3 of PORT1

P1IE |= BIT3 | BIT2; //enable interrupt on P1.3

#ifdef HW_SPI

//enable SDI, SDO and SCLK, master mode, MSB first, output enabled, held in reset state

// SMCLK / 16

USICKCTL = USIDIV_4 + USISSEL_2; //TODO sw solution

// clock phase

USICTL1 |= USICKPH; //TODO sw solution

// USI release from reset

USICTL0 &= ~USISWRST; //TODO sw solution

#endif

}

#ifdef HW_SPI

uint16_t rf12_write_cmd(uint16_t data)

{

nSEL_LOW;

USISR = data; //load SPI data register

USICTL1 &= ~USIIFG; //clear SPI interrupt

USICNT = USI16B | 16;//select 16 bit data size and select 16 bits to be received/transmitted

while((USICTL1 & USIIFG) != 0x01) //wait for data transmitted interrupt

{

}

nSEL_HIGH;

return USISR;

}

#else

uint16_t rf12_write_cmd(uint16_t rf12data)

{

uint16_t return_data = 0;

uint8_t i;

nSEL_LOW;

for(i = 0; i < 15; i++)

{

if(rf12data & 0x8000)

SDO_HIGH;

else

SDO_LOW;

SCK_HIGH;

if(P1IN & SDI)

return_data++;

return_data = return_data << 1;

SCK_LOW;

rf12data = rf12data << 1;

}

nSEL_HIGH;

return return_data;

}

#endif

void rf12_init(void)

{

rf12_write_cmd(0x0000);

rf12_write_cmd(0x80E8);

rf12_write_cmd(RF_TX_ON);

rf12_write_cmd(0xA680);

rf12_write_cmd(0xC647);

rf12_write_cmd(0x94A2);

rf12_write_cmd(0xC2AC);

rf12_write_cmd(0xCA83);

rf12_write_cmd(0xCED4);

rf12_write_cmd(0xC483);

rf12_write_cmd(0x9855);

rf12_write_cmd(0xCC77);

rf12_write_cmd(0xE000);

rf12_write_cmd(0xC800);

rf12_write_cmd(0xC049);

}

void rf12_write_data(uint16_t data)

{

while(P1IN & BIT3)

{

}

rf12_write_cmd(0xB800 + data);

}

void FIFOReset(void)

{

rf12_write_cmd(0xCA81);

rf12_write_cmd(0xCA83);

}

unsigned int rfRecv(void)

{

unsigned int data;

data = rf12_write_cmd(0xB000);

return (data & 0x00FF);

}

unsigned char waitForData(void)

{

SDO_LOW;

nSEL_LOW;

SCK_HIGH;

if(P1IN & BIT7)

{

SCK_LOW;

SDO_HIGH;

nSEL_HIGH;

return 1;

}

else

{

SCK_LOW;

SDO_HIGH;

nSEL_HIGH;

return 0;

}

#endif /* RFM12B_SLEMI_TX_H_ */

Now all we need to do is to connect RFM12B module to microcontroller, upload our code and start it. At start, green LED should be on for about a second and after that both red and green LED should blink every two seconds, showing us when it is transmitting.

For receiver we need to create new project as before. This time I will name it RFM12B_RX_002. We also need to create new header file, I will name it rfm12b_slemi_rx. I add rx and tx at the end of files, so that I know which is which, if I have both open at the same time, when writing or editing code.

Here is our main.c code:

/*
 * Created by Slemi
 * 7.3.2018
 */

#include <msp430.h>
#include "rfm12b_slemi_rx.h"

#define key_press !(P1IN & 0x08)
volatile uint16_t podatki[16];
volatile uint16_t rx_data[16];

int main(void)
{
	uint8_t i;
	uint16_t rx_data[16];
	WDTCTL = WDTPW | WDTHOLD;	// Stop watchdog timer
	//set clock to 1MHz
	BCSCTL1 = CALBC1_1MHZ;
	DCOCTL = CALDCO_1MHZ;

	/* Clock configuration. CPU is running at ~1MHz */
	BCSCTL1 &= ~(XTS);  // Select low frequency mode for LFXT1, high frq mode not supported on MSP430G2231
	BCSCTL1 |= DIVA_3;  // ACLK = 32768Hz / 8 = 4096Hz
	BCSCTL3 &= ~(LFXT1S0 | LFXT1S1);	//32768-Hz crystal on LFXT1

	//wait for RFM21B to wake up
	__delay_cycles(1000000);

	rf12_port_init();
	rf12_init();

	_enable_interrupt();
	rf12_write_cmd(RF_RX_ON);
	FIFOReset();
	while(1)
	{
		for(i = 0; i < 16; i++)
		{
			while(!(waitForData()));
			rx_data[i] = rf12_write_cmd(0xB000) & 0x00FF;
		}
		if(rx_data[4] == 0x0034)
			izh0_on;
		_delay_cycles(100000);
		izh0_off;
		FIFOReset();
	}
	return 0;
}

void __attribute__((interrupt(PORT1_VECTOR)))
PORT1_ISR(void)
{
	if(P1IFG & BIT3)
	{
		P1IFG &= ~BIT3;  //clear interrupt flag
	}
	if(P1IFG & BIT2)
	{
		P1OUT |= BIT1;
		P1IFG &= ~BIT2;  //clear interrupt flag
	}
}

* Created by Slemi

* 7.3.2018

#include <msp430.h>

#include "rfm12b_slemi_rx.h"

#define key_press !(P1IN & 0x08)

volatile uint16_t podatki[16];

volatile uint16_t rx_data[16];

int main(void)

{

uint8_t i;

uint16_t rx_data[16];

WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer

//set clock to 1MHz

BCSCTL1 = CALBC1_1MHZ;

DCOCTL = CALDCO_1MHZ;

/* Clock configuration. CPU is running at ~1MHz */

BCSCTL1 &= ~(XTS); // Select low frequency mode for LFXT1, high frq mode not supported on MSP430G2231

BCSCTL1 |= DIVA_3; // ACLK = 32768Hz / 8 = 4096Hz

BCSCTL3 &= ~(LFXT1S0 | LFXT1S1); //32768-Hz crystal on LFXT1

//wait for RFM21B to wake up

__delay_cycles(1000000);

rf12_port_init();

rf12_init();

_enable_interrupt();

rf12_write_cmd(RF_RX_ON);

FIFOReset();

while(1)

{

for(i = 0; i < 16; i++)

{

while(!(waitForData()));

rx_data[i] = rf12_write_cmd(0xB000) & 0x00FF;

}

if(rx_data[4] == 0x0034)

izh0_on;

_delay_cycles(100000);

izh0_off;

FIFOReset();

}

return 0;

}

void __attribute__((interrupt(PORT1_VECTOR)))

PORT1_ISR(void)

{

if(P1IFG & BIT3)

{

P1IFG &= ~BIT3; //clear interrupt flag

}

if(P1IFG & BIT2)

{

P1OUT |= BIT1;

P1IFG &= ~BIT2; //clear interrupt flag

}

And here is code for rfm12b_slemi_rx.h:

/*
 * Created by Slemi
 * 7.3.2018
 */

#ifndef RFM12B_SLEMI_RX_H_
#define RFM12B_SLEMI_RX_H_

#include <msp430.h>
#include <stdint.h>

#define HW_SPI

// SDI, SDO refers to msp430 device's pins, NOT RFM12B's
#define SDI     BIT7		// to SDO
#define SDO     BIT6		// to SDI
#define SCK     BIT5		// to SCK
#define SEL     BIT4		// to nSEL
#define IRQ			BIT3		// to nIRQ
#define RED_LED BIT0
#define GRN_LED BIT6

// RF12 command codesTODO change
#define RF_RX_ON  0x82DD
#define RF_TX_ON   0x823D
#define RF_IDLE_MODE    0x820D
#define RF_SLEEP_MODE   0x8205
#define RF_WAKEUP_MODE  0x8207
#define RF_TXREG_WRITE  0xB800
#define RF_RX_FIFO_READ 0xB000
#define RF_WAKEUP_TIMER 0xE000

#define izh0_on		P1OUT |= BIT0
#define izh0_off	P1OUT &= ~BIT0
#define izh1_on		P1OUT |= BIT1
#define izh1_off	P1OUT &= ~BIT1
/*#define izh2_on		P1OUT |= BIT2
 #define izh2_off	P1OUT &= ~BIT2*/

#define nSEL_LOW 	P1OUT &= ~(SEL)
#define nSEL_HIGH	P1OUT |= (SEL)
#define SDO_HIGH	P1OUT |= (SDO)
#define SDO_LOW		P1OUT &= ~(SDO)
#define SCK_HIGH	P1OUT |= (SCK)
#define SCK_LOW		P1OUT &= ~(SCK)

void rf12_port_init(void);
uint16_t rf12_write_cmd(uint16_t rf12data);
void rf12_init(void);
void rf12_write_data(uint16_t data);
void FIFOReset(void);
unsigned int rfRecv(void);
unsigned char waitForData(void);

void rf12_port_init(void)
{
	P1DIR |= SCK | SDO | SEL | RED_LED | BIT1 | BIT2;	//outputs
	P1OUT &= ~BIT2 & ~BIT1 & ~BIT0;
	P1DIR &= ~SDI & ~BIT3 & ~BIT2;	//input
	//init ports
	P1REN |= BIT7 | BIT3 | BIT2;  //Enable pull-up resistor for button/RFM12B IRQ
	P1OUT |= BIT7 | BIT3 | BIT2;  //Set input for key high for enabling detection of keypress or IRQ
	P1IFG &= ~BIT3 & ~BIT2;  //clear interrupt flag for bit3 of PORT1
	P1IE |= BIT3 | BIT2;		//enable interrupt on P1.3
#ifdef HW_SPI
	//enable SDI, SDO and SCLK, master mode, MSB first, output enabled, held in reset state
	USICTL0 = USIPE7 | USIPE6 | USIPE5 | USIMST | USIOE | USISWRST;  //TODO sw solution

	// SMCLK / 16
	USICKCTL = USIDIV_4 + USISSEL_2;		//TODO sw solution

	// clock phase
	USICTL1 |= USICKPH;		//TODO sw solution

	// USI release from reset
	USICTL0 &= ~USISWRST;		//TODO sw solution
#endif
}

#ifdef HW_SPI
uint16_t rf12_write_cmd(uint16_t data)
{
	nSEL_LOW;
	USISR = data;	//load SPI data register
	USICTL1 &= ~USIIFG;  //clear SPI interrupt
	USICNT = USI16B | 16;//select 16 bit data size and select 16 bits to be received/transmitted
	while((USICTL1 & USIIFG) != 0x01)	//wait for data transmitted interrupt
	{
	}
	nSEL_HIGH;
	return USISR;
}
#else
uint16_t rf12_write_cmd(uint16_t rf12data)
{
	uint16_t return_data = 0;
	uint8_t i;
	nSEL_LOW;
	for(i = 0; i < 15; i++)
	{
		if(rf12data & 0x8000)
		SDO_HIGH;
		else
		SDO_LOW;
		SCK_HIGH;
		if(P1IN & SDI)
		return_data++;
		return_data = return_data << 1;
		SCK_LOW;
		rf12data = rf12data << 1;
	}
	nSEL_HIGH;
	return return_data;
}
#endif

void rf12_init(void)
{
	rf12_write_cmd(0x0000);
	rf12_write_cmd(0x80E8);
	rf12_write_cmd(RF_RX_ON);
	rf12_write_cmd(0xA680);
	rf12_write_cmd(0xC647);
	rf12_write_cmd(0x94A2);
	rf12_write_cmd(0xC2AC);
	rf12_write_cmd(0xCA83);
	rf12_write_cmd(0xCED4);
	rf12_write_cmd(0xC483);
	rf12_write_cmd(0x9855);
	rf12_write_cmd(0xCC77);
	rf12_write_cmd(0xE000);
	rf12_write_cmd(0xC800);
	rf12_write_cmd(0xC049);
}

void rf12_write_data(uint16_t data)
{
	while(P1IN & BIT3)
	{
	}
	rf12_write_cmd(0xB800 + data);
}

void FIFOReset(void)
{
	rf12_write_cmd(0xCA81);
	rf12_write_cmd(0xCA83);
}

unsigned int rfRecv(void)
{
	unsigned int data;
	data = rf12_write_cmd(0xB000);
	return (data & 0x00FF);
}

unsigned char waitForData(void)
{
	SDO_LOW;
	nSEL_LOW;
	SCK_HIGH;
	if(P1IN & BIT7)
	{
		SCK_LOW;
		SDO_HIGH;
		nSEL_HIGH;
		return 1;
	}
	else
	{
		SCK_LOW;
		SDO_HIGH;
		nSEL_HIGH;
		return 0;
	}
}

#endif /* RFM12B_SLEMI_RX_H_ */

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* Created by Slemi

* 7.3.2018

#ifndef RFM12B_SLEMI_RX_H_

#define RFM12B_SLEMI_RX_H_

#include <msp430.h>

#include <stdint.h>

#define HW_SPI

// SDI, SDO refers to msp430 device's pins, NOT RFM12B's

#define SDI BIT7 // to SDO

#define SDO BIT6 // to SDI

#define SCK BIT5 // to SCK

#define SEL BIT4 // to nSEL

#define IRQ BIT3 // to nIRQ

#define RED_LED BIT0

#define GRN_LED BIT6

// RF12 command codesTODO change

#define RF_RX_ON 0x82DD

#define RF_TX_ON 0x823D

#define RF_IDLE_MODE 0x820D

#define RF_SLEEP_MODE 0x8205

#define RF_WAKEUP_MODE 0x8207

#define RF_TXREG_WRITE 0xB800

#define RF_RX_FIFO_READ 0xB000

#define RF_WAKEUP_TIMER 0xE000

#define izh0_on P1OUT |= BIT0

#define izh0_off P1OUT &= ~BIT0

#define izh1_on P1OUT |= BIT1

#define izh1_off P1OUT &= ~BIT1

/*#define izh2_on P1OUT |= BIT2

#define izh2_off P1OUT &= ~BIT2*/

#define nSEL_LOW P1OUT &= ~(SEL)

#define nSEL_HIGH P1OUT |= (SEL)

#define SDO_HIGH P1OUT |= (SDO)

#define SDO_LOW P1OUT &= ~(SDO)

#define SCK_HIGH P1OUT |= (SCK)

#define SCK_LOW P1OUT &= ~(SCK)

void rf12_port_init(void);

uint16_t rf12_write_cmd(uint16_t rf12data);

void rf12_init(void);

void rf12_write_data(uint16_t data);

void FIFOReset(void);

unsigned int rfRecv(void);

unsigned char waitForData(void);

void rf12_port_init(void)

{

P1DIR |= SCK | SDO | SEL | RED_LED | BIT1 | BIT2; //outputs

P1OUT &= ~BIT2 & ~BIT1 & ~BIT0;

P1DIR &= ~SDI & ~BIT3 & ~BIT2; //input

//init ports

P1REN |= BIT7 | BIT3 | BIT2; //Enable pull-up resistor for button/RFM12B IRQ

P1OUT |= BIT7 | BIT3 | BIT2; //Set input for key high for enabling detection of keypress or IRQ

P1IFG &= ~BIT3 & ~BIT2; //clear interrupt flag for bit3 of PORT1

P1IE |= BIT3 | BIT2; //enable interrupt on P1.3

#ifdef HW_SPI

//enable SDI, SDO and SCLK, master mode, MSB first, output enabled, held in reset state

// SMCLK / 16

USICKCTL = USIDIV_4 + USISSEL_2; //TODO sw solution

// clock phase

USICTL1 |= USICKPH; //TODO sw solution

// USI release from reset

USICTL0 &= ~USISWRST; //TODO sw solution

#endif

}

#ifdef HW_SPI

uint16_t rf12_write_cmd(uint16_t data)

{

nSEL_LOW;

USISR = data; //load SPI data register

USICTL1 &= ~USIIFG; //clear SPI interrupt

USICNT = USI16B | 16;//select 16 bit data size and select 16 bits to be received/transmitted

while((USICTL1 & USIIFG) != 0x01) //wait for data transmitted interrupt

{

}

nSEL_HIGH;

return USISR;

}

#else

uint16_t rf12_write_cmd(uint16_t rf12data)

{

uint16_t return_data = 0;

uint8_t i;

nSEL_LOW;

for(i = 0; i < 15; i++)

{

if(rf12data & 0x8000)

SDO_HIGH;

else

SDO_LOW;

SCK_HIGH;

if(P1IN & SDI)

return_data++;

return_data = return_data << 1;

SCK_LOW;

rf12data = rf12data << 1;

}

nSEL_HIGH;

return return_data;

}

#endif

void rf12_init(void)

{

rf12_write_cmd(0x0000);

rf12_write_cmd(0x80E8);

rf12_write_cmd(RF_RX_ON);

rf12_write_cmd(0xA680);

rf12_write_cmd(0xC647);

rf12_write_cmd(0x94A2);

rf12_write_cmd(0xC2AC);

rf12_write_cmd(0xCA83);

rf12_write_cmd(0xCED4);

rf12_write_cmd(0xC483);

rf12_write_cmd(0x9855);

rf12_write_cmd(0xCC77);

rf12_write_cmd(0xE000);

rf12_write_cmd(0xC800);

rf12_write_cmd(0xC049);

}

void rf12_write_data(uint16_t data)

{

while(P1IN & BIT3)

{

}

rf12_write_cmd(0xB800 + data);

}

void FIFOReset(void)

{

rf12_write_cmd(0xCA81);

rf12_write_cmd(0xCA83);

}

unsigned int rfRecv(void)

{

unsigned int data;

data = rf12_write_cmd(0xB000);

return (data & 0x00FF);

}

unsigned char waitForData(void)

{

SDO_LOW;

nSEL_LOW;

SCK_HIGH;

if(P1IN & BIT7)

{

SCK_LOW;

SDO_HIGH;

nSEL_HIGH;

return 1;

}

else

{

SCK_LOW;

SDO_HIGH;

nSEL_HIGH;

return 0;

}

#endif /* RFM12B_SLEMI_RX_H_ */

After running it, it should blink at the same rate as transmitter. I hope it works in first try for you!

This is just bare project, just to get started. If we need some transmission checking, we should at least add checksum, or even better two way transmission, so that we can check back if data was sent ok, or we need to retransmit. But this is for another tutorial…

Thank you for reading!

Gregor