FLY E185
Service Manual
CKT Confidential
Page 14 of 47
I/Q Swap:
By setting “1” to IQSWP in TX_CFG control register, phase on I/Q plane will rotate in inverse
direction. This option is to meet the different requirement form RF chip regarding I/Q plane. This
control signal is for GMSK Modulation only.
Modulation Bypass Mode:
For DSP debug purpose, set both “1” for MDBYP (Modulator Bypass) in TX_CFG control
register and BYPFLR(Bypass RX Filter) in RX_CFG control register for directly loopback DSP
16-bits data (10bits valid data plus sign or zero extension) through DAC only.
Modulation Output Latency Adjustment:
For multiple bursts, there maybe are consecutive bursts with different modulation mode. However,
there are about 8 to 10 QB output latencies for either GMSK/8PSK modulation output. In order to
match the transition timing of power ramp control in the power amplifier outside the baseband
chip, we have to precisely control the SW_QBCNT (Modulation Switching Quarter Bit Count) in
TX_CFG control register. Which will program the mode switching timing in QB count, and the
default value to switch the modulation mode is 24 QB count. Additionally, by programming
GMSK_DTAP_SYM (GMSK Delay Tap) in TX_CFG and GMSK_DTAP_QB in TX_CON
control register, the output latency for GMSK modulation output can be adjust to compensate the
offset between GMSK/8PSK modulator. The GMSK_DTAP_SYM adjust the output latency in
symbol time, while GMSK_DTA_QB adjust in Quarter Bit (QB) Time. Default value is delay 1
symbol of GMSK modulator output.
Modulation Bypass Mode:
For DSP debug purpose, set both “1” for MDBYP (Modulator Bypass) in TX_CFG control
register and BYPFLR (Bypass RX Filter) in RX_CFG control register for directly loopback DSP
16-bits data through DAC only.
Force GMSK Modulator turn on:
By setting “1” to APNDEN (Append Enable) bit in TX CFG control register, GMSK modulator
and 8PSK modulator will park on constant DC level during the non-burst period, while the I/Q
pair output phase maybe discontinuous since both modulator will be reset at the beginning of the
burst. However, the reset of the modulator will be helpful for the debugging purpose.
