TTGO esp32 with tft display

[priisdk]

I have just bought a TTGO esp32 with tft display. After 3 hours of struggling I managed to flash the firmware and bring life to the color display. However, I still have (at least) 3 problems:

1. The example below works fine but changing the text and adding more graphics has no effect when I rerun the program - until I disconnect and reconnect the board. How can I clear the screen (tft.clear() seems to have no effect) without disconnecting the board?

import machine, display, time, math, network, utime
tft = display.TFT()
tft.init(tft.ST7789,bgr=False,rot=tft.LANDSCAPE, miso=17,backl_pin=4,backl_on=1, mosi=19, clk=18, cs=5, dc=16)
tft.setwin(40,52,320,240)
#tft.clear()
for i in range(0,241):
color=0xFFFFFF-tft.hsb2rgb(i/241*360, 1, 1)
tft.line(i,0,i,135,color)
#tft.clearWin(0x000000)
tft.set_fg(0x000000)
tft.set_bg(0x113355)
tft.ellipse(120,67,120,67)
tft.line(0,0,240,135)
tft.line(240,0,0,135)
text="TTGO!"
tft.text(120-int(tft.textWidth(text)/2),67-int(tft.fontSize()[1]/2),text,0x987654)

2. When I try to connect to wifi with the procedure below:
   def connecttowifi(username,password):
   import network
   global mywifi
   mywifi = network.WLAN(network.STA_IF)
   mywifi.active(True)
   while not mywifi.isconnected():
   mywifi.connect(username, password)
   utime.sleep_ms(10)

I get the following error message:
**W (503546) [modnetwork]: WiFi not started
False
W (503647) wifi: wifi osi_nvs_open fail ret=4353

E (503648) wifi: wifi_init_in_caller_task 707 ret=4353
E (503648) [modnetwork]: Error initializing WiFi (4353)
Traceback (most recent call last):
File "", line 34, in
File "", line 28, in connecttowifi
OSError: 4353**

How can I make it work?

3. When I run a somewhat larger program (468 lines of code) I get the following error message:
   MemoryError: memory allocation failed, allocating 308 bytes
   Is my program really too long for my board or is there a way to make my board accept it?
   I used the following simple (!) command to flash the firmware:

C:\esptoolmaster2>python esptool.py --chip esp32 --port COM14 --baud 460800 --before default_reset --after no_reset write_flash -z --flash_mode dio --flash_freq 40m --flash_size detect 0x1000 bootloader.bin 0xf000 phy_init_data.bin 0x10000 MicroPython.bin 0x8000 partitions_mpy.bin

Can I do better by changing something in this command? Or is there a better firmware?

Poul Riis

[kjm1102]

1. Not familiar with that display but sometimes power cycling an oled can be a quick & dirty way of clearing it till you track down a better way.
2. ESP32 OdroidGo: Error initializing WiFi (4353) loboris/MicroPython_ESP32_psRAM_LoBo#230 might help?
3. You could use mpy_cross to convert your .py to .mpy. In my case it compacts 500 line/60k .py files down to ~19k which will usually fit into ram OK. Simply change your boot.py to a one liner, import code, & it will run code.mpy for you.

[robert-hh]

About topic 2:
You have to call connect() only once. In the loop waiting for the connection you can use is_connected() to test, whether the connection is done. I use the following function since years:

def do_connect():
    import network
    import time

    wlan = network.WLAN(network.STA_IF) # create station interface
    wlan.active(True)       # activate the interface
    if not wlan.isconnected():      # check if the station is connected to an AP
        wlan.ifconfig((WIFI_IP, "255.255.255.0", WIFI_DNS, GOOGLE_DNS))
        wlan.connect(WIFI_SSID, WIFI_PASSWD) # connect to an AP

        for _ in range(10):
            if wlan.isconnected():      # check if the station is connected to an AP
                break
            print('.', end='')
            time.sleep(1)
        else:
            print(" Connect attempt timed out\n")
            return
    print('\nnetwork config:', wlan.ifconfig())

About topic 3: Like @kjm1102 said, you might get out of that using pre-compiled code, especially if you get the error during import of code. When you have large data objects, pre-compiling might not help. Sometime it helps to call gc.collect() in the main loop of your code, reducing somewhat memory fragmentation. The device does not seem to have PSRAM, so you are limited to the internal RAM. But a ~500 lines of code should fit, unless as said you have large data objects. What helps is freezing your code into flash. Then the code resies in flash and not in RAM. But for that you have to build the firmware yourself.

[kloetpatra]

1. The example below works fine but changing the text and adding more graphics has no effect when I rerun the program - until I disconnect and reconnect the board. How can I clear the screen (tft.clear() seems to have no effect) without disconnecting the board?

Got the same problem. Changing text and re-run main.py does not change anything on the display until hard-reset. Also the tft methods within the REPL seem to not have any effect after the script has run. Only the backlight switching works.

[peterhinch]

If it's the TTGO T-display it is supported by nano-gui and micro-gui.

[peterhinch]

The TTGO T-display is 135x240 pixels and it uses 16 bit color, consequently the buffer size is 64,800 bytes. The driver used in the GUIs listed above reduces this by a factor of 4 to 16,200 bytes which leaves a lot more headroom for code. The tradeoff is that you can only display 16 different 16-bit colors at a time.