Hello,
I tried to use HL8548 UART sleep mode with AT+KSLEEP=0 with following sequence.
- wait for starting up of HL8548
- send “AT+KSLEEP=0”
- reset HL8548
- wait for starting up of HL8548
- toggle UART1_DTR pin (1.8V bufferring with VGPIO)
- send “ATI3”
=> there is no response from HL8548
These were same result with UART flowcontrol on/off case(AT&K0 and AT&K3).
So I checked UART1_DTR pin (pin #7) with oscilloscope. It showed 0.5V!!!
And I remove 1.8V buffer which drive UART1_DTR signal and checked UART1_DTR pin,
and then HL8548 drives UART1_DTR pin with 1.8V!! Signal is collided.
My Question is,
- My wakeup sequence is correct?
- Spec says UART1_DTR is input, but it drives High(1.8V) signal.
Is this spec or hardware bug? - please tell me workaround for this behaviour.
Best regards,