Frequently Asked Questions |ROHM Semiconductor

The system waits while changing channels until the receiver receives the radio wave from the transmitter. Is there anything to be aware of about this system?
- The receiver changes channels until it receives radio waves from the sender. For this reason, the transmission side must keep sending the preamble until the receiver detects the transmitted channel. Therefore, taking into account the number of channels to search for radio waves, a long preamble is required. Also, if there is only a radio wave, the receiving side may make an erroneous channel determination based on radio waves from other systems. For this reason, it is necessary to consider the "criterion for presence of radio waves (bit synchronization information, etc.)" that uses signals other than radio waves.
  Related Products: ML7344/ML7406 family, ML7345 family, ML7396 family, ML7404, ML7414

If there is interference (when radio waves simultaneously transmitted from different transmitters collide), it may be impossible to receive data (SyncWord or addresses) in the first place. Is there a way to avoid missing data to be received due to collision?
- If data is transmitted simultaneously on the same channel, it may become unable to receive the data due to the RF interference characteristics. However, ARIB STD T-108 requires CCA to be performed before transmission. For this reason, there is a mechanism to avoid interference due to simultaneous transmission from nearby transmitters.
  Related Products: ML7344/ML7406 family, ML7345 family, ML7396 family, ML7404, ML7414

For the VCO upper limit frequency setting (B1_0x51) for VCO adjustment, a value larger than the one obtained from the calculation formula described in the data sheet is set in the register (B1_0x51). What are the specific advantages/disadvantages of setting the register (B1_0x51) to “0.75 MHz” or “48 MHz” when, for instance, the calculated value is 0.4 MHz?
- If the calculated value is 0.4 MHz, selecting 0.75 MHz makes the frequency more accurate whereas selecting 48 MHz will reduce the accuracy.
  Since the VCO calibration obtains the capacitance correction values at the lower and upper points, and calculates the capacitance correction value at the set frequency by linear interpolation, the error becomes larger as the calibration frequency range increases. Therefore, select a VCO upper limit frequency setting that is slightly wider than the operating frequency.
  Related Products: ML7344/ML7406 family, ML7345 family, ML7404, ML7414

What is the procedure for repeating the IQ adjustments twice or more?
- When performing the second and subsequent IQ adjustments, restore IQ_MAG_ADJ[11:0]([IQ_MAG_ADJ_L: B0 0x5A(3-0)],[IQ_MAG_ADJ_L: B0 0x5B])=0x800,[IQ_PHASE_ADJ_H/L: B0 0x5C/5D]=0x0000, then start the adjustment.
  Related Products: ML7345 family, ML7404, ML7414