I am glad that Hugen finally decides to release the NanoVNA H4 product, based on F303 and 4" LCD. He kept improving the design that I didn't know when he would be satisfied. Besides these two main features, there are some other improvements.
- RF front-end circuit on noise and sensitivity improvement.
- Power management circuit.
- Larger battery capacity.
- UART and two other GPIO pins are brought out to allow for Bluetooth, BLE, or any other connections.
- Jog switch sensitivity.
- Enter DFU by pressing down the jog switch at power-on. The LCD screen will be black at DFU mode. We have to do so since the software jump to DFU mode doesn't work for F303.
Initially, I was thinking of using NanoVNA to learn ChibiOS, but I disliked the flash size of STM32F072. So I contacted Hugen to discuss the possibility of replacing F072 with larger MCU, and invited him to join this forum. Here, Hugen received lots of feedback from the community. So he decided to make the F303 based NanoVNA with larger LCD. We contacted the NanoVNA's original author Takahashi san (edy555), who is an enthusiast in promoting RF engineering. He gave Hugen some advices. Currently he is planning a new project. Maybe it's another VNA covering higher frequency and better sensitivity, or maybe another useful tool. We will know soon.
For this project, I worked on the software porting to F303, used ChibiOS's ADC API for touchscreen, and ported the LCD display controller to ST7796S to support 320x480 4" LCD. Hugen carefully verified my codes and fixed some GUI issue and used larger fonts. He also incorporated some improvements and suggestions from GitHub users, including edy555, cho45, qrp73, Pmax65, etc.
The NanoVNA-H4 and NanoVNA-F took different approaches to provide larger screen. NanoVNA-F is an excellent product with larger, bright and high resolution LCD, larger battery, metal case, and is FreeRTOS based; while Hugen and I think that keep price low and continue to use software based on original NanoVNA code could better promote community involvement.
There are still places to be improved, such as the touchscreen responsiveness. Hugen and I will post firmwareupdate if we have any fix.
Kudos to Takahashi san for his innovative NanoVNA design and willing to share, to Hugen for his meticulous effort to drive down the cost and improve performance, and to everyone for your supports and suggestions.
73
Ken Liao, AA6KL
