jankae / lcr Goto Github PK

Fontend.cpp says

static constexpr uint32_t referenceVoltage = 1100000;

I think this should be Vbias0 (1.11 V, ie, 1110000) rather than the reference voltage for the DAC (1.1 V, ie, 1100000). Probably doesn't hurt and gets fixed by calibration anyway.

Im using the same TFT(Base on SSD1289) but the touch driver has changed to newer version (ADS7843 to XPT2046)
Can you update the touch library ( im trying to modify the new one but unsuccessful) Thank you very much.

Start.cpp says

constexpr float ReferenceTypical = 1.2f;

but the typical value for the Internal reference voltage of the STM32F303 is 1.23 V according to the datasheet. Harmless.

The STM32F303xC datasheet says:

No external termination series resistors are required on USB_DP (D+) and USB_DM (D-), the matching impedance is already included in the embedded driver.

In consequence, R21 and R22 should be populated with 0 Ω resistors.

The firmware kept crashing due to memory corruption in log_write() until I disabled logging. Now I've enabled logging and investigated the issue:

If a floating-point number format format (such as %f) is used and newlib-nano is compiled with floating-point support (FLOATING_POINT is defined) but is used without printf support for floating-point numbers (like this project does), _svfprintf_r() (which is called by vsnprintf() etc.) will add the value of uninitialized variable n to the variable accumulating the number of output characters for the return value. The result is that the return value of vsnprintf() will be a random number which is most likely quite positive or quite negative.

log_write() adds that value to the number of characters written (variable "written"), which will become negative or quite big and in consequence will make the final snprintf() call write to some random location. Also, code following that call using "written" will break.

There's probably no point in reporting this issue against newlib-nano-1.0 or newlib-nano-2 as there has been no activity for a decade. Maybe I manage to report this issue to ST.

Enabling floating-point support for printf() in the project properties fixes the problem.

In the schematic, reference resistor R9 has a value of 1 kΩ, in the source code (lines 587 and 588 of Frontend.cpp), a value of 1.5 kΩ is used for the reference resistor.