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# STM32WB55 Formula for converting RAW RSSI value in dBm

Associate II

Dear Sir,

I'm new to STM32WB55 and using STM32CubeMonitor-RF.

We see the value of RAW RSSI from the Value parameter of Command Complete of ACI_HAL_READ_RAW_RSSI in STM32CubeMonitor-RF and it results in the RSSI dBm.

Such as:

0x000006 --> -107.00 dBm

0x000007 --> -107.00 dBm

0x00000A --> -106 dBm

0x00000B --> -105.00 dBm

0x000012 --> -103.00 dBm

0x000014 --> -102.00 dBm

0x000017 --> -100.00 dBm

0x00001C --> -98.00 dBm

0x00001D --> -98.00 dBm

0x000021 --> -97.00 dBm

0x000024 --> -97.00 dBm

0x000029 --> -96.00 dBm

...

0x0001A9 --> -75.00 dBm

Sincerely yours,

David

1 ACCEPTED SOLUTION

Accepted Solutions
ST Employee
``````  int32_t rsi_dbm;
uint32_t reg_agc;

// extract the data rssi_int16 + agc

// check if rssi is too low
if((rssi_int16 == 0U) || (reg_agc > 0xbU))
{
rsi_dbm = 127 ;
}
else
{
rsi_dbm = (int32_t)reg_agc * 6 - 127 ;
{
rsi_dbm += 6 ;
}

rsi_dbm += (int32_t)(uint32_t)((417U*rssi_int16 + 18080U)>>10) ;
}

// result is in rsi_dbm ;``````

reg_agc = 0x07 (High 1 byte of RSSI Level value)

result -> -33.00dBm

You can refer to the above formula.

9 REPLIES 9
Evangelist III

Associate II

We noticed the description in an5270 adhere:

and an5378 for Figure 10. ACI_HAL_READ_RAW_RSSI in STM32CubeMonitor-RF packet rate exchange configuration.

Is there datasheet about the Formula for converting the RAW RSSI value in dBm? Thank you.

Sincerely yours,

David

ST Employee
``````  int32_t rsi_dbm;
uint32_t reg_agc;

// extract the data rssi_int16 + agc

// check if rssi is too low
if((rssi_int16 == 0U) || (reg_agc > 0xbU))
{
rsi_dbm = 127 ;
}
else
{
rsi_dbm = (int32_t)reg_agc * 6 - 127 ;
{
rsi_dbm += 6 ;
}

rsi_dbm += (int32_t)(uint32_t)((417U*rssi_int16 + 18080U)>>10) ;
}

// result is in rsi_dbm ;``````

reg_agc = 0x07 (High 1 byte of RSSI Level value)

result -> -33.00dBm

You can refer to the above formula.

Evangelist III

@Sean Park​ - even ST Employees don't know how to properly post source code to their own forum? :\

ST Employee

I'm sorry. thanks for pointing out

Associate II

Sincerely thank you for your kind solution.

Sincerely yours,

David

Evangelist III

@DLan.1​ - Please mark the solution:

Associate II

Dear Sir,

Thank you for your kind help.

Associate II

Dear Sir,

Thank you for your kind help.

Sincerely yours,

David