MMR-70 - cheap radio module
some experiments with the fm module that features an atmega32
This will be my take on the Sony Ericsson MMR70 radio modules that feature an atmega32 on board. There are not all pins from the atmega32 broken out on the board, but for 70cents you get a decent mictrocontroller and a FM transmitter with SPI and I2C pins broken out.
My first project aims to reduce the material count from the
https://hackaday.io/project/3508-portable-trollmaster-3000 project. I have the timer2 under my control now, so I should be able to transmit morse code over radio soon.
MMR-70 - cheap radio module | pimping the board
2015-09-12 17:51:32
I thought about using the Talkie library for arduino with this module, inspired by #Gas Sensor For Emergency Workers , but it is written for 16 MHz and I would have to deal with timers (again). 16MHz resonators are ordered - although I'm not certain that the atmega32L will work properly at 16MHz and 2.8V. I will look into that, but will also order 8MHz resonators as well and maybe a new LDO for 3.3v? I'm also waiting for some 2x3 pin headers for easier programming via an ISP connector and might make a labeled board... idk.
MMR-70 - cheap radio module | pimping the board
2015-09-12 17:51:32
I thought about using the Talkie library for arduino with this module, inspired by #Gas Sensor For Emergency Workers , but it is written for 16 MHz and I would have to deal with timers (again). 16MHz resonators are ordered - although I'm not certain that the atmega32L will work properly at 16MHz and 2.8V. I will look into that, but will also order 8MHz resonators as well and maybe a new LDO for 3.3v? I'm also waiting for some 2x3 pin headers for easier programming via an ISP connector and might make a labeled board... idk.
MMR-70 - cheap radio module | program progress
2015-09-04 10:50:23
So with the help of the code from #Portable Trollmaster 3000 I was able to set up the module in no time. It works on the atmega32 (no real surprise here). I've made some little changes to the program - I set the sending power all the way up with the help of the datasheet and also worked on the following function. This should make it easier to set the frequency.
void set_frequency(unsigned long frequency)
{
unsigned long factor = frequency / 8192;
unsigned int upper = (uint8_t) (factor >> 8);
unsigned int lower = (uint8_t) ((factor << 8) >>8);
Wire.beginTransmission(NS731_I2C_addr);
Wire.write((uint8_t) 0x0a);
Wire.write((uint8_t) lower);
Wire.write((uint8_t) upper);
Wire.endTransmission();
}
updated function, removed not needed type castings etc. (thanks to @al1 )
void set_frequency(unsigned long frequency)
{
unsigned long factor = frequency / 8192;
uint8_t upper = factor >> 8;
uint8_t lower = factor;
Wire.beginTransmission(NS731_I2C_addr);
Wire.write((uint8_t) 0x0a);
Wire.write(lower);
Wire.write(upper);
Wire.endTransmission();
}
MMR-70 - cheap radio module | program progress
2015-09-04 10:50:23
So with the help of the code from #Portable Trollmaster 3000 I was able to set up the module in no time. It works on the atmega32 (no real surprise here). I've made some little changes to the program - I set the sending power all the way up with the help of the datasheet and also worked on the following function. This should make it easier to set the frequency.
void set_frequency(unsigned long frequency)
{
unsigned long factor = frequency / 8192;
unsigned int upper = (uint8_t) (factor >> 8);
unsigned int lower = (uint8_t) ((factor << 8) >>8);
Wire.beginTransmission(NS731_I2C_addr);
Wire.write((uint8_t) 0x0a);
Wire.write((uint8_t) lower);
Wire.write((uint8_t) upper);
Wire.endTransmission();
}
updated function, removed not needed type castings etc. (thanks to @al1 )
void set_frequency(unsigned long frequency)
{
unsigned long factor = frequency / 8192;
uint8_t upper = factor >> 8;
uint8_t lower = factor;
Wire.beginTransmission(NS731_I2C_addr);
Wire.write((uint8_t) 0x0a);
Wire.write(lower);
Wire.write(upper);
Wire.endTransmission();
}
MMR-70 - cheap radio module | Video
MMR-70 - cheap radio module | Video
MMR-70 - cheap radio module | Pinout of the module
2015-09-03 14:57:14
There actually is already a good pinout picture, but I wanted to correct the voltage and be on the safe side when it comes to copyrights - so I fired up inkscape.
https://cdn.hackaday.io/images/5263531441284885620.png
MMR-70 - cheap radio module | Pinout of the module
2015-09-03 14:57:14
There actually is already a good pinout picture, but I wanted to correct the voltage and be on the safe side when it comes to copyrights - so I fired up inkscape.
https://cdn.hackaday.io/images/5263531441284885620.png
MMR-70 - cheap radio module | sketch for timer
2015-08-31 14:33:40
int output_pin = 15;
int randNumber;
ISR (TIMER2_COMP_vect)
{
PORTD ^= ( 1 << PD7 );
}
void setup()
{
randomSeed(analogRead(0));
DDRD = ( 1 << PD7 );
TCCR2 = (1 << WGM21);
TCCR2 |= (1 << CS20);
TCCR2 |= (1 << CS21);
OCR2 = 131 - 1;
TIMSK |= (1<<OCIE2);
sei();
}
void loop()
{
randNumber = random(256);
OCR2 = randNumber;
delay(250);
}
MMR-70 - cheap radio module | sketch for timer
2015-08-31 14:33:40
int output_pin = 15;
int randNumber;
ISR (TIMER2_COMP_vect)
{
PORTD ^= ( 1 << PD7 );
}
void setup()
{
randomSeed(analogRead(0));
DDRD = ( 1 << PD7 );
TCCR2 = (1 << WGM21);
TCCR2 |= (1 << CS20);
TCCR2 |= (1 << CS21);
OCR2 = 131 - 1;
TIMSK |= (1<<OCIE2);
sei();
}
void loop()
{
randNumber = random(256);
OCR2 = randNumber;
delay(250);
}