ePaper optimisations.

README.md

@@ -149,7 +149,7 @@ development so check for updates.
  7.4 [Class TSequence](./README.md#74-class-tsequence) Plotting realtime, time sequential data.  
 8. [ESP32 touch pads](./README.md#8-esp32-touch-pads) Replacing buttons with touch pads.  
 9. [Realtime applications](./README.md#9-realtime-applications) Accommodating tasks requiring fast RT performance.  
- 9.1 [ePaper refresh](./README.md#91-epaper-refresh) Using these techniques to provide a full refresh.  
+10. [ePaper displays](./README.md#10-epaper-displays) Using these techniques to provide a full refresh.  
 
 [Appendix 1 Application design](./README.md#appendix-1-application-design) Tab order, button layout, encoder interface, use of graphics primitives  
 [Appendix 2 Freezing bytecode](./README.md#appendix-2-freezing-bytecode) Optional way to save RAM.  
@@ -509,7 +509,7 @@ of slow and visually intrusive refreshing. However there is an exception: the
 [Waveshare pico_epaper_42](https://www.waveshare.com/pico-epaper-4.2.htm). This
 supports partial updates which work remarkably well with minimal ghosting. Note
 that it can be used with hosts other than the Pico via the supplied cable. See
-[ePaper refresh](./README.md#91-epaper-refresh).
+[ePaper displays](./README.md#10-epaper-displays).
 
 Display drivers are documented [here](https://github.com/peterhinch/micropython-nano-gui/blob/master/DRIVERS.md).
 
@@ -3042,7 +3042,7 @@ another from occurring.
 ```
 The demo `gui/demos/audio.py` provides example usage.
 
-## 9.1 ePaper refresh
+# 10 ePaper displays
 
 The [Waveshare pico_epaper_42](https://www.waveshare.com/pico-epaper-4.2.htm)
 is currently the only fully supported ePaper display, with a hardware_setup.py
@@ -3051,7 +3051,7 @@ initial refresh the driver is put into partial mode to provide reasonably
 quick and visually satisfactory response to button events. However ghosting may
 accumulate after long periods of running, and an application may occasionally
 need to perform a full refresh. This requires the "done" interlock described
-above.
+in section 9.
 
 ```python
 async def full_refresh():

drivers/epaper/pico_epaper_42.py

@@ -94,6 +94,12 @@ EPD_partial_lut_bb1 = b"\x00\x19\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00
 \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
 \x00\x00\x00\x00"
 
+@micropython.viper
+def _linv(dest:ptr8, source:ptr8, length:int):
+    for n in range(length):
+        c = source[n]
+        dest[n] = c ^ 0xFF
+
 class EPD(framebuf.FrameBuffer):
     # A monochrome approach should be used for coding this. The rgb method ensures
     # nothing breaks if users specify colors.
@@ -245,33 +251,41 @@ class EPD(framebuf.FrameBuffer):
     def ready(self):
         return not (self._busy or (self.busy_pin() == 0))  # 0 == busy
 
-    def _line(self, n, buf=bytearray(_BWIDTH)):
+    @micropython.native
-        img = self.mvb
+    def _line(self, start, buf=bytearray(_BWIDTH)):  # Sending 50 bytes 40us at 10MHz, 12ms for 300 lines
-        s = n * _BWIDTH
+        _linv(buf, self.mvb[start:], _BWIDTH)  # Invert image data for EPD
-        for x, b in enumerate(img[s : s + _BWIDTH]):
-            buf[x] = b ^ 0xFF
         self.send_bytes(buf)
 
-    async def _as_show(self):
+    # Timing @10MHz/250MHz: full refresh 2.1s, partial 740ms
+    # Blocking with split=5 740/5=150ms
+    async def _as_show(self, split):
         self.send_command(b"\x13")
-        for j in range(_EPD_HEIGHT):  # Loop would block ~300ms
+        lps = _EPD_HEIGHT // split
-            self._line(j)
+        idx = 0
+        #ttt = time.ticks_ms()
+        for _ in range(split):  # For each segment
+            for _ in range(lps):
+                self._line(idx)
+                idx += _BWIDTH
             await asyncio.sleep_ms(0)
+        #print("Time", time.ticks_diff(time.ticks_ms(), ttt))
         self._updated.set()
-        self.send_command(b"\x12")  # Async .display_on()
+        self.send_command(b"\x12")  # Nonblocking .display_on()
         while not self.busy_pin():
-            await asyncio.sleep_ms(10)  # About 1.7s
+            await asyncio.sleep_ms(0)  # About 1.7s for full refresh
         self._busy = False
+        #print("Time", time.ticks_diff(time.ticks_ms(), ttt))  # ~630ms
 
     async def do_refresh(self, split):  # For micro-gui
-        await self._as_show()
+        assert (not self._busy), "Refresh while busy"
+        await self._as_show(split)  # split=5
 
-    def show(self):
+    def show(self):  # nanogui
         if self._busy:
             raise RuntimeError('Cannot refresh: display is busy.')
         self._busy = True  # Immediate busy flag. Pin goes low much later.
         if self._asyn:
-            asyncio.create_task(self._as_show())
+            asyncio.create_task(self._as_show(5))  # split into 5 segments
             return
         self.send_command(b"\x13")
         for j in range(_EPD_HEIGHT):

gui/demos/epaper.py

@@ -119,7 +119,7 @@ class FooScreen(Screen):
         Checkbox(wri, row, col, callback=self.cbcb)
         col+= 40
         self.led = LED(wri, row, col, color=YELLOW, bdcolor=GREEN)
-        CloseButton(wri)
+        CloseButton(wri, bgcolor=BLACK)
         asyncio.create_task(run(dial, lbltim, m0, scale))
 
 
@@ -174,10 +174,9 @@ async def run(dial, lbltim, m0, scale):
 
 
 def test():
-    if ssd.height < 240 or ssd.width < 320:
+    print('Testing micro-gui...')
-        print(' This test requires a display of at least 320x240 pixels.')
+    Screen.change(FooScreen)
-    else:
+    print("End")
-        print('Testing micro-gui...')
+    ssd.sleep()  # Tidy shutdown of EPD
-        Screen.change(FooScreen)
 
 test()

hardware_setup.py

@@ -29,7 +29,6 @@
 
 from machine import Pin, SPI, freq
 import gc
-
 from drivers.epaper.pico_epaper_42 import EPD as SSD
 freq(250_000_000)  # RP2 overclock
 # Create and export an SSD instance
@@ -37,7 +36,8 @@ prst = Pin(9, Pin.OUT, value=1)
 pcs = Pin(10, Pin.OUT, value=1)
 pdc = Pin(8, Pin.OUT, value=0)  # Arbitrary pins
 busy = Pin(15, Pin.IN)
-spi = SPI(0, sck=Pin(6), mosi=Pin(7), miso=Pin(4), baudrate=4_000_000)
+# Datasheet allows 10MHz
+spi = SPI(0, sck=Pin(6), mosi=Pin(7), miso=Pin(4), baudrate=10_000_000)
 gc.collect()  # Precaution before instantiating framebuf
 
 # Using normal socket connection default args apply

setup_examples/pico_epaper_42_pico.py

@@ -29,7 +29,6 @@
 
 from machine import Pin, SPI, freq
 import gc
-
 from drivers.epaper.pico_epaper_42 import EPD as SSD
 freq(250_000_000)  # RP2 overclock
 # Create and export an SSD instance
@@ -37,7 +36,8 @@ prst = Pin(9, Pin.OUT, value=1)
 pcs = Pin(10, Pin.OUT, value=1)
 pdc = Pin(8, Pin.OUT, value=0)  # Arbitrary pins
 busy = Pin(15, Pin.IN)
-spi = SPI(0, sck=Pin(6), mosi=Pin(7), miso=Pin(4), baudrate=4_000_000)
+# Datasheet allows 10MHz
+spi = SPI(0, sck=Pin(6), mosi=Pin(7), miso=Pin(4), baudrate=10_000_000)
 gc.collect()  # Precaution before instantiating framebuf
 
 # Using normal socket connection default args apply