Holtek BC45B4523, Manual, Page: 82 / 96

Rev. 1.20 82 October 28, 2020
BC45B4523
RxFilterTune Command
Command
Code
Action
Input Data Required
in FIFO
Return Data
Read from FIFO
Interrupt
Flag
0x10
Activate the filter-frequency-corner-tuning
process in receiver amplifier
— — IdleIRq
The RxFilterTune command activates the filter-frequency-corner-tuning process in the receiver amplifier. This
command is for adjusting the filter frequency corner due to variations in temperature and manufacturing process.
After operating the command, all frequency corners are set back to the proper values and the frequency deviation
is eliminated. The tuning process takes 302μs. However, this command is automatically performed every time the
system is powered up. Therefore, it is not required to tune the filter by users frequently.
LFOTune Command
Command
Code
Action
Input Data Required
in FIFO
Return Data Read
from FIFO
Interrupt
Flag
0x20
Activate the low frequency tuning process to
generate clock 16.38kHz
— — IdleIrq
The LFOTune command activates the low frequency oscillator tuning process. This command is for adjusting
the low frequency clock frequency due to variations in temperature and manufacturing process. After operating
the command, output frequency is set back to suitable value, 16.38kHz. However, this command is automatically
performed every time the system is powered up. Therefore, it is not required to tune the LFO by users frequently.
ADCCalibrate Command
Command
Code
Action
Input Data Required
in FIFO
Return Data Read
from FIFO
Interrupt
Flag
0x21 Calibrate ADC to record the ADC offset value — — IdleIrq
The ADCCalibrate command enables ADC calibration process. This command will start ADC conversion without
input signal by disabling transmitter. The ADC result output, ADC_Result_Offset, both I and Q channel are kept
into internal buffer. These offset values will be later used for compensating ADC_Result value both in Card
Detection and Field Detection operation.
Note that this command should be re-executed when ADC configuration parameters in the “Registers Associated
with Field Detection and Card Detection” table presented in the “RF Amplitude Detector System” section are
changed. Furthermore, users should be ensured that there is no external RF source device near by the reader.
CardDetect Command
Command
Code
Action
Input Data Required
in FIFO
Return Data
Read from FIFO
Interrupt
Flag
0x22
Activate ADC to measure RF amplitude at
pin RX by enabling the device’s transmitter
— —
IdleIRq,
CDIRq
The CardDetect command starts the Card Detection operation as described in the “RF Amplitude Detector
System” section. The device senses RF amplitude, driving from its transmitter, at pin RX, and uses ADC to
convert into digital ADC Result. After operation is completed, IdleIRq flag is set. If the ADC_Result is more than
CDThreshold_H, or lower than CDThreshold_L, CDIRq flag will also be set at the same time. To ensure suitable
operation of card detection, users should firstly find the ADC baseline level, ADC_Result run on free air.
FieldDetect Command
Command
Code
Action
Input Data Required
in FIFO
Return Data Read
from FIFO
Interrupt
Flag
0x23
Activate ADC to measure external RF
amplitude at pin RX from other RF source by
disabling the device’s transmitter
— —
IdleIRq,
RxIRq