Convert long term and short term RSSI to dBm

This article applies to:
DolphinAPI

QUESTION

I am using radio_getRSSI but I would like to convert the values to dBm. How can I do it with the API ?

ANSWER

You can use the radio_rssiToDbm_asm. In your source code add the definition of the function as shown below:

definition

/************************************************************************************************************************//*!
Calculates dBm from RSSI based on the calibration values in radio init specified by array u8RssiCalib.
\param      RSSI signal where the LSB bit is the LNA
\return     dBm value, 
 
<b>Number of nested functions:</b> -\n
<b>Typical execution time:</b> -us
 
\note
This value is supposed to be interpreted as a negative value although the function returns an unsigned value
 
\sa radio_getRSSI
**************************************************************************************************************************/
uint8 radio_rssiToDbm_asm(uint16 u16RssiLna);

With the result uin16 value call the function radio_rssiToDbm_asm and you will get the dBm result. This function is already defined in the API Version 2.2.0.0.

EXAMPLE CODE:
This example shows how to get the LongTerm RSSI and transmit it through the UART.

main.c

#include "EO3000I_API.h"
#include "EO3000I_CFG.h"
#include "stdio.h"
#include "string.h"
 
 
uint8 radio_rssiToDbm_asm(uint16 u16RssiLna);
void main()
{
  uint16 pu16StRssi, pu16LtRssi;
  uint8 u8Buff[30];
  uint8 u8dBmLtRssi;
 
  mainInit();
  radio_enableRx(1);
 
  while(1)
  {
 
    radio_getRSSI (&pu16StRssi, &pu16LtRssi);
 
    u8dBmLtRssi = radio_rssiToDbm_asm(pu16LtRssi);
    sprintf(u8Buff,"Long Term RSSI: %u dBm\n", (uint16)u8dBmLtRssi);
    while (uart_sendBuffer(u8Buff, strlen(u8Buff))!=OK);
    time_wait(500);
  }
}

EO3000I_CFG.h

// Generated with DolphinStudio 2.0.0.13 which was compiled on Jun  2 2010 05:10:30
//Generated on 24.01.2011 14:48 by DolphinStudio 2.1.1.0
 
#ifndef _EO3000I_CFG_H_INCLUDED
#define _EO3000I_CFG_H_INCLUDED
#include "EO3000I_API.h"
 
 
//! Function Prototypes
void radio_init_asm(RADIO_INIT_PARAM u8PowerUp);
void startupInit();
void mainInit();
 
 
//*********************UART PARAM***************************
 
//! UART Rx/Tx buffers allocation
#define RX_RING_SIZE 34
#define TX_RING_SIZE 34
 
extern volatile uint8	xdata	u8RxRing[RX_RING_SIZE];
extern volatile uint8	xdata	u8TxRing[TX_RING_SIZE];
 
extern uint8 uart_param[];
 
//*********************RADIO PARAM***************************
#define RADIO_BUFF_NUM 10
#define RADIO_MATURITY_TIME 100
 
//! Radio buffers allocation	
 extern volatile uint8 xdata u8gRadioBuff[RADIO_BUFF_NUM][RADIO_BUFF_LENGTH];	
 //! Radio tx buffers additional allocation for state 		
 extern volatile uint8 xdata u8gRadioBuffTXState[RADIO_BUFF_NUM];		
 //! Radio flags		
 extern volatile uint8 idata u8gFlags[RADIO_BUFF_NUM];	
 //! buffers Rx subtelegrams counters. Index indicates the buffer number.	
 extern volatile uint8 idata u8gRadioBuffsRxSubtel[RADIO_BUFF_NUM];		
 //! buffers Tx subtelegrams counters. Index indicates the buffer number. 		
 extern volatile uint8 idata u8gRadioBuffsTxSubtel[RADIO_BUFF_NUM];	
 //! buffers time stamp counters. Index indicates the buffer number.	
 extern volatile uint8 idata u8gRadioBuffsTimeStamp[RADIO_BUFF_NUM];	
 //! buffers received bytes counters. Index indicates the buffer number.		
 extern volatile uint8 idata u8gRadioBuffsBytes[RADIO_BUFF_NUM];	
 //! buffers dBm values. Value indicating signal strength upon telegram reception. 
 extern volatile uint8 xdata u8gRxRadioBuffsDbm[RADIO_BUFF_NUM];	
 //! Tx buffers time to send subtelegram. Index indicates the buffer number. 
 extern volatile uint8 idata u8gTxRadioBuffsTimeToSend[RADIO_BUFF_NUM];
 
//*********************FILTER PARAM***************************
 
//! Max. number of filters
#define FILTER_NUM	4
 
//! Filter buffer allocation for value of filter
extern volatile uint32 xdata u32gFilterValue[FILTER_NUM];
//! Filter buffer allocation containing FILTER_TYPE (Bit 0..1 and FILTER_KIND Bit 7)
extern volatile uint8  xdata u8gFilterCfg[FILTER_NUM];
 
extern uint8 filter_param[];
 
//*********************IO PARAM***************************
 
extern uint8 code	io_param[];
 
#endif //_EO3000I_CFG_H_INCLUDED

EO3000I_CFG.c

//Generated on 24.01.2011 14:48 by DolphinStudio 2.1.1.0
#include "EO3000I_CFG.h"
 
 
//*********************API INIT*************************** 
 
//Note: Function is called from startup.a51. Global variables are not yet initialized!
void startupInit()
{
	pwr_enableXTAL(DEFAULT_DELAY);
	io_init(io_param);
}
 
 
//Note: Function is called from main()
void mainInit()
{
	radio_init_asm(CFG_ALL);
	radio_init(RADIO_BUFF_NUM, RADIO_MATURITY_TIME);
	UART_INIT(uart_param, SET_ALL_PARAM);
	isr_timer0Init();
	misc_init();
	pwr_selectXTAL();
	ISD51_INIT(BAUD_57600);
}
 
//*********************UART PARAM***************************
 
//! UART Rx/Tx buffers allocation
volatile uint8	xdata	u8RxRing[RX_RING_SIZE];
volatile uint8	xdata	u8TxRing[TX_RING_SIZE];
 
uint8 uart_param[]	= {	
 		BAUD_9600,		//IDX_BAUD 
 		RX_RING_SIZE,	//IDX_RX_RING_SIZE 
 		TX_RING_SIZE,	//IDX_TX_RING_SIZE 
 };
 
 
//*********************RADIO PARAM***************************
 
//! Radio buffers allocation	
 volatile uint8 xdata u8gRadioBuff[RADIO_BUFF_NUM][RADIO_BUFF_LENGTH];	
 //! Radio tx buffers additional allocation for state 		
 volatile uint8 xdata u8gRadioBuffTXState[RADIO_BUFF_NUM];		
 //! Radio flags		
 volatile uint8 idata u8gFlags[RADIO_BUFF_NUM];	
 //! buffers Rx subtelegrams counters. Index indicates the buffer number.	
 volatile uint8 idata u8gRadioBuffsRxSubtel[RADIO_BUFF_NUM];		
 //! buffers Tx subtelegrams counters. Index indicates the buffer number. 		
 volatile uint8 idata u8gRadioBuffsTxSubtel[RADIO_BUFF_NUM];	
 //! buffers time stamp counters. Index indicates the buffer number.	
 volatile uint8 idata u8gRadioBuffsTimeStamp[RADIO_BUFF_NUM];	
 //! buffers received bytes counters. Index indicates the buffer number.		
 volatile uint8 idata u8gRadioBuffsBytes[RADIO_BUFF_NUM];	
 //! buffers dBm values. Value indicating signal strength upon telegram reception. 
 volatile uint8 xdata u8gRxRadioBuffsDbm[RADIO_BUFF_NUM];	
 //! Tx buffers time to send subtelegram. Index indicates the buffer number. 
 volatile uint8 idata u8gTxRadioBuffsTimeToSend[RADIO_BUFF_NUM];
 
//*********************FILTER PARAM***************************
 
//! Filter buffer allocation for value of filter
volatile uint32 xdata u32gFilterValue[FILTER_NUM];
//! Filter buffer allocation containing FILTER_TYPE (Bit 0..1 and FILTER_KIND Bit 7)
volatile uint8  xdata u8gFilterCfg[FILTER_NUM];
 
uint8 filter_param[]	= {
 		FILTER_NUM, //IDX_FILTER_MAX
 		FILTER_ALL_AND	//IDX_FILTER_OPERATOR 
 };
 
//*********************IO PARAM***************************
 
uint8 code	io_param[]	= {	
 		0x07,	//IDX_GPIO_CONF 
 		0x00,	//IDX_GPIO0_CONF 
 		0x0E,	//IDX_GPIO0_PULL_CONF 
 		0x01,	//IDX_GPIO0_DIR 
 		0x00,	//IDX_GPIO1_AN 
 		0xC0,	//IDX_GPIO1_CONF 
 		0x03,	//IDX_GPIO1_DIG_CONF 
 		0x80,	//IDX_GPIO1_DIR 
 		0x7F,	//IDX_GPIO1_PULL 
 		0x04,	//IDX_GPIO2_CONF 
 		0x00,	//IDX_GPIO2_DIR 
 		0x00,	//IDX_GPIO0 
 		0x00,	//IDX_GPIO1 
 		0x00 	//IDX_GPIO2 
 };
 
// I/O Configuration overview
// 
//      Pin:  Interface     Direction  Pull   Init Value
// SCSEDIO0:  Digital I/O   Out        None   0
// SCLKDIO1:  Digital I/O   In         Up     0
// WSDADIO2:  Digital I/O   In         Up     0
// RSDADIO3:  Digital I/O   In         Up     0
//    ADIO0:  Digital I/O   In         Up     0
//    ADIO1:  Digital I/O   In         Up     0
//    ADIO2:  Digital I/O   In         Up     0
//    ADIO3:  Digital I/O   In         Up     0
//    ADIO4:  Digital I/O   In         Up     0
//    ADIO5:  Digital I/O   In         Up     0
//    ADIO6:  UART          In         Up     0
//    ADIO7:  UART          Out        None   0
//   WXIDIO:  Digital I/O   In         Up     0
//   WXODIO:  Digital I/O   In         Up     
//    WAKE0:  Digital I/O   In         None   
//    WAKE1:  Digital I/O   In         None