Hi, I am trying to check the oscillator tuning of our boards and did some reference testing with a WB55 Nucleo. using aci_hal_tone_start. Using 0,0 I do get an output near 2.402GHz, but not quite were I would expect it. The header says the following:
/**
* @brief ACI_HAL_TONE_START
* This command starts a carrier frequency, i.e. a tone, on a specific channel.
* The frequency sine wave at the specific channel may be used for debugging
* purpose only. The channel ID is a parameter from 0x00 to 0x27 for the 40 BLE
* channels, e.g. 0x00 for 2.402 GHz, 0x01 for 2.404 GHz etc.
* This command should not be used when normal Bluetooth activities are
* ongoing.
* The tone should be stopped by ACI_HAL_TONE_STOP command.
*
* @PAram RF_Channel BLE Channel ID, from 0x00 to 0x27 meaning (2.402 +
* 0.002*0xXX) GHz
* Device will continuously emit 0s, that means that the tone will be at
* the channel center frequency minus the maximum frequency deviation
* (250 kHz).
* Values:
* - 0x00 ... 0x27
* @PAram Freq_offset Frequency Offset for tone channel
* Values:
* - 0x00 ... 0xFF
* @return Value indicating success or error code.
*/
tBleStatus aci_hal_tone_start( uint8_t RF_Channel,
uint8_t Freq_offset );
Especially: Device will continuously emit 0s, that means that the tone will be at the channel center frequency minus the maximum frequency deviation (250 kHz).
So my expectation would be for parameters 0,0 to lead to 2.401750GHz. But actually on the Nucleo I get nearly clean 2.402GHz and on our board I get something around 2.0421000GHz. Even the later can still do functioning BLE communication. So is the documentation just off and really tone DOES put out the center frequency of the requested channel or am I misunderstanding something else?
