(Firmware) SPI using GPIO : The code

#ifndef __SPI__H__
#define __SPI__H__

extern unsigned char time_y = 8;

void SPI_Master_GPIO_Init(void)
{
PC_DDR|=(1<<6 mosi="" nbsp="" span="">
PC_CR1|=(1<<6 span="">
PC_CR2&=~(1<<6 span="">

PC_DDR|=(1<<5 nbsp="" span="">
PC_CR1|=(1<<5 span="">
PC_CR2&=~(1<<5 span="">

PA_DDR|=(1<<3 nbsp="" out="" span="">
PA_CR1|=(1<<3 span="">
PA_CR2&=~(1<<3 span="">

PC_DDR&=~(1<<7 in="" miso="" nbsp="" span="">
PC_CR1|=(1<<7 span="">
PC_CR2&=~(1<<7 span="">
}

void CSN_low (void)
{
PA_ODR &= ~(1<<3 span="">
}

void CSN_high (void)
{
PA_ODR |= (1<<3 span="">
}


void SPI_Slave_GPIO_Init(void)
{
PC_DDR&=~(1<<6 span="">
PC_CR1|=(1<<6 span="">
PC_CR2&=~(1<<6 span="">

PC_DDR&=~(1<<5 span="">
PC_CR1|=(1<<5 span="">
PC_CR2&=~(1<<5 span="">

PA_DDR&=~(1<<3 span="">
PA_CR1|=(1<<3 span="">
PA_CR2&=~(1<<3 span="">

PC_DDR|=(1<<7 span="">
PC_CR1|=(1<<7 span="">
PC_CR2&=~(1<<7 span="">
}




void send_char (unsigned int temp)
{
unsigned char j = 0, i = 0;

for(i=0;i<8 i="" span="">
{

j = 7-i;
PC_ODR &= ~(1<<5 span="">

if((temp>>j) & 0x01)
PC_ODR |= (1<<6 span="">
else
PC_ODR &= ~(1<<6 span="">

time_y = 8;
 while(time_y--);
PC_ODR |= (1<<5 span="">
 time_y = 8;
 while(time_y--);
PC_ODR &= ~(1<<5 span="">
}

}




unsigned char get_char (void)
{
unsigned char j = 0, i = 0;

for(i=0;i<8 i="" span="">
{
unsigned char k = 7-i;

PC_ODR &= ~(1<<5 span="">



time_y = 8;
 while(time_y--);
PC_ODR |= (1<<5 span="">

if(PC_IDR & (1<<7 span="">
{
j |= (1<
 }
else
time_y = 8;
 while(time_y--);
PC_ODR &= ~(1<<5 span="">

}
return j;

}

void write_n_byte (unsigned char add,unsigned char no_of_byte,unsigned char *string_data)
{
unsigned char i = 0;
add |=0x20;
send_char(add);
for (i = 0; i < no_of_byte ; i++)
{
send_char(*string_data+i);
}
}








#endif

RF modules

A comparison among various available RF module/IC :-

Part No.	Tx - Power (dBm)	Rx - Power (dBm)	Current consumption (mA)	Range (m)	Data Transmission rate	Operating Frequency (MHz)	Price (Rupees)	Protocol supported	Special Feature
RFM22/3B	+20/+13	-121	85/30  18.5	600	256 KBPS	ISM band	800 (module)	RF	LBD & TS
SPIRIT 1	+11/+16	-118	21      9	200	500 KBPS	ISM band	160 (IC)	RF	LBD & TS Carrier sns whitening
TC32306FTG	+10	-116	12      9.7	00		ISM band	300(IC)	RF
LE-50-433/868	14	-109	45     26	2000	115.2 KBPS	ISM band		RF
nRF24L01+	0	-82 -85 -94	11.3   13.5	50	2 MBPS 1 MBPS 250 KBPS	ISM band	250	RF
MRF89XAM9A	+10	-105 -111	25      3	100	25 KBPS 2 KBPS	ISM band	500(module)	RF
SiFLEX02-R2	24	-102	285     30	3200	40 KBPS	900 MHz	3000(module)	RF  & Zigbee	With antenna
TarangF4L	0	-92	45      50		250 KBPS	ISM band		RF  & Zigbee	With antenna
Xbee			45      50	30	~250 KBPS	ISM band	1000(module)	Zigbee
MDBT40	+4	-93	16     12.6	80	250 KBPS	ISM band	500(module)	BLE
nRF51422	+4	-93	10.5    13	100	2 MBPS	ISM band	1000 (module)	BLE
HC06	+6	-80	40     30	50	2 MBPS	ISM band	300(module)	BLE
EMB-TRX169PA	+27	-122	385    27	>500	200 KBPS	169 MHz	(module)	RF	External antenna rqd

LBD : Low Battery Detection

TS  : Temperature Sensor