micropython · markb139 · Jan 18, 2023 · Jan 20, 2023 · Feb 3, 2023 · Feb 3, 2023
diff --git a/.gitignore b/.gitignore
@@ -23,3 +23,6 @@ user.props
 
 # MacOS desktop metadata files
 .DS_Store
+
+# VScode config
+.vscode
diff --git a/docs/rp2/general.rst b/docs/rp2/general.rst
@@ -34,3 +34,4 @@ The peripherals include:
 * 16 PWM channels
 * USB 1.1 controller
 * 8 PIO state machines
+* 12 DMA channels and 4 pacing timers
diff --git a/docs/rp2/quickref.rst b/docs/rp2/quickref.rst
@@ -298,6 +298,50 @@ See :ref:`machine.WDT <machine.WDT>`. ::
 
 The maximum value for timeout is 8388 ms.
 
+DMA (Direct memory access)
+--------------------------
+
+The RP2040 has a DMA subsytem that has 12 hardware controlled DMA channels and 4 pacing timers.
+
+Example using DMA to fade an LED::
+
+    from rp2 import DMA, Timer
+    from machine import Pin, PWM
+
+    led = Pin(16, Pin.OUT)
+    pwm1 = PWM(led)
+    pwm1.freq(1000)
+    pwm1.duty_u16(0)
+
+    # PWM 0A for GPIO16. Lower 16 bits of CC
+    dest = 0x4005000e 
+    dma = DMA()
+    dma.claim()
+    t = Timer()
+
+    t.claim()
+    # go as slowly as possible
+    t.set(0x0001, 0xffff)
+
+    data_size = dma.DMA_SIZE_16
+    buffer_size = 32768
+    from_buffer = bytearray(buffer_size)
+    for i in range(0, buffer_size, 2):
+        from_buffer[i]= i & 0xff
+        from_buffer[i+1]= (i>>8) & 0xff
+
+    dma.write_from(from_buffer=from_buffer,
+                   to_address=dest,
+                   transfer_count=buffer_size>>data_size,
+                   dreq=dreq,
+                   data_size=data_size)
+    while dma.isbusy():
+        time.sleep_ms(1)
+
+    t.unclaim()
+    dma.unclaim()
+
+
 OneWire driver
 --------------
 

diff --git a/examples/rp2/dma_write_from.py b/examples/rp2/dma_write_from.py
@@ -0,0 +1,59 @@
+import time
+from rp2 import DMA, Timer
+from machine import Pin, PWM
+
+
+def led():
+    print("DMA write_from demo")
+    led = Pin(16, Pin.OUT)
+    pwm1 = PWM(led)
+    pwm1.freq(1000)
+    pwm1.duty_u16(0)
+
+    # pwm 0A attached to GPIO 16
+    dest = 0x4005000E
+    dma = DMA()
+    dma.claim()
+    t = Timer()
+
+    X = 0x0001
+    Y = 0xFFFF
+    t.claim()
+    t.set(X, Y)
+
+    print(f"Starting\nDMA:{dma}\nTimer:{t}")
+
+    dreq = t.dreq()
+
+    data_size = dma.DMA_SIZE_16
+    buffer_size = 32768
+    from_buffer = bytearray(buffer_size)
+
+    # create a 16 bit fade
+    for i in range(0, buffer_size, 2):
+        from_buffer[i] = i & 0xFF
+        from_buffer[i + 1] = (i >> 8) & 0xFF
+
+    start = time.ticks_ms()
+
+    dma.write_from(
+        from_buffer=from_buffer,
+        to_address=dest,
+        transfer_count=buffer_size >> data_size,
+        dreq=dreq,
+        data_size=data_size,
+    )
+    while dma.isbusy():
+        time.sleep_ms(100)
+
+    end = time.ticks_ms()
+
+    t.unclaim()
+    dma.unclaim()
+    print(f"Write from fade took {end-start}mS")
+    print("Done")
+    pwm1.duty_u16(0)
+
+
+if __name__ == "__main__":
+    led()
diff --git a/examples/rp2/dma_write_from_irq.py b/examples/rp2/dma_write_from_irq.py
@@ -0,0 +1,77 @@
+import uasyncio
+import time
+from rp2 import DMA, Timer
+from machine import Pin, PWM
+
+
+async def led():
+    print("DMA write_from demo")
+    led = Pin(16, Pin.OUT)
+    pwm1 = PWM(led)
+    pwm1.freq(1000)
+    pwm1.duty_u16(0)
+
+    # pwm 0A attached to GPIO 16
+    dest = 0x4005000E
+    dma = DMA()
+    dma.claim()
+    t = Timer()
+
+    # slow the timer to it's slowest rate
+    X = 0x0001
+    Y = 0xFFFF
+    t.claim()
+    t.set(X, Y)
+
+    print(f"Starting\nDMA:{dma}\nTimer:{t}")
+
+    dreq = t.dreq()
+
+    data_size = dma.DMA_SIZE_16
+    buffer_size = 32768
+    from_buffer = bytearray(buffer_size)
+
+    # create a 16 bit fade
+    for i in range(0, buffer_size, 2):
+        from_buffer[i] = i & 0xFF
+        from_buffer[i + 1] = (i >> 8) & 0xFF
+
+    start = time.ticks_ms()
+
+    e = uasyncio.ThreadSafeFlag()
+
+    def _callback(dma_status):
+        print("callback")
+        e.set()
+
+    dma.write_from(
+        from_buffer=from_buffer,
+        to_address=dest,
+        transfer_count=buffer_size >> data_size,
+        dreq=dreq,
+        data_size=data_size,
+        handler=_callback,
+    )
+
+    await e.wait()
+
+    end = time.ticks_ms()
+
+    t.unclaim()
+    dma.unclaim()
+    print(f"Write from fade took {end-start}mS")
+    print("Done")
+    pwm1.duty_u16(0)
+
+
+async def async_led():
+    t = uasyncio.create_task(led())
+    await t
+
+
+def main():
+    uasyncio.run(async_led())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/ports/rp2/CMakeLists.txt b/ports/rp2/CMakeLists.txt
@@ -109,6 +109,7 @@ set(MICROPY_SOURCE_PORT
     fatfs_port.c
     machine_adc.c
     machine_bitstream.c
+    dma.c
     machine_i2c.c
     machine_i2s.c
     machine_pin.c
@@ -140,6 +141,7 @@ set(MICROPY_SOURCE_QSTR
     ${MICROPY_DIR}/shared/runtime/mpirq.c
     ${MICROPY_DIR}/shared/runtime/sys_stdio_mphal.c
     ${PROJECT_SOURCE_DIR}/machine_adc.c
+    ${PROJECT_SOURCE_DIR}/dma.c
     ${PROJECT_SOURCE_DIR}/machine_i2c.c
     ${PROJECT_SOURCE_DIR}/machine_i2s.c
     ${PROJECT_SOURCE_DIR}/machine_pin.c

diff --git a/ports/rp2/README.md b/ports/rp2/README.md
@@ -10,7 +10,7 @@ Currently supported features are:
 - `uos` module with VFS support.
 - `machine` module with the following classes: `Pin`, `ADC`, `PWM`, `I2C`, `SPI`,
   `SoftI2C`, `SoftSPI`, `Timer`, `UART`, `WDT`.
-- `rp2` module with programmable IO (PIO) support.
+- `rp2` module with programmable IO (PIO) support and DMA module.
 
 See the `examples/rp2/` directory for some example code.