TX1 is low when powered by Vdd

[caz]

When CubeCell HTCC-AB02S is powered by 3.3V Vdd, i.e. not by USB, TX1 is low and does not move. It moves between 0 and 3.2V when powered by USB. Is it by design? If I short Vdd and Vin, TX1 becomes active? Its schematic has a black box on USB/Battery/Vdd/Charging.

[jasonXu]

Hi,

please refer this topic:

CubeCell-GPS 6502: issue with UART0 pins when powered from battery

hi, We got the result. This was what we designed for low power consumption. The situation is roughly like this: When USB is powered, the serial port chip CP2102 will be powered on, and RX1 will be pulled to a high level . When you use this statement “Serial.begin();” in your code, the level of RX1 will be automatically detected. If RX1 is high, the serial port will be opened, so TX1 can The waveform is detected. When only battery powered, cp2102 is not poweredand RX1 is not powered on either…

[caz]

Jason,
Thank you for the information. I confirmed that UART_RX level is not high(1), Serial1, i.e. TX1/RX1 is not initialized in your CubeCell/1.2.0/cores/asr650x/Serial/HardwareSerial.cpp. I have data on TX1 when I make it always initialize. Please make this case as Solved.

[Supporter]

Hi.
We did this to avoid power goes high when use battery.
you can add
pinMode(UART_RX,OUTPUT);
digitalWrite(UART_RX,1);
before Serial.begin();
I think this will work.

[Supporter]

Hi caz,
We updated the lowpower mode, uart work even UART_RX is low level. You can update from git , and do not need to do my last suggestion.

[caz]

I successfully built SoftRF, Linar’s project with your latest code. It seems you also fixed the problem I reported in SoftRF’s forum. It is “ADC_IN1 reports 0.2V when powered by Vdd”. It now reports 1.15V. Still something strange. I expect 1.65V.

[jasonXu]

The max value adc can read is 2399mV. if your need read higher value ，you can use a voltage divider circuit.