72 lines
2.1 KiB
Python
72 lines
2.1 KiB
Python
from micropython import const
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import digitalio
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SRAM_SEQUENTIAL_MODE = const(1 << 6)
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class Adafruit_MCP_SRAM(object):
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SRAM_READ = 0x03
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SRAM_WRITE = 0x02
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SRAM_RDSR = 0x05
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SRAM_WRSR = 0x01
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def __init__(self, cs_pin, spi):
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# Handle hardware SPI
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self.spi_device = spi
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self._cs = cs_pin
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self._cs.direction = digitalio.Direction.OUTPUT
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while not self.spi_device.try_lock():
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pass
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self._cs.value = False
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self.spi_device.write(bytearray([Adafruit_MCP_SRAM.SRAM_WRSR, 0x43]))
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self._cs.value = True
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self.spi_device.unlock()
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def write(self, addr, buf, reg=SRAM_WRITE):
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cmd = bytearray([reg, (addr >> 8) & 0xFF, addr & 0xFF] + buf)
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while not self.spi_device.try_lock():
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pass
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self._cs.value = False
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self.spi_device.write(cmd)
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self._cs.value = True
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self.spi_device.unlock()
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def read(self, addr, length, reg=SRAM_READ):
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cmd = bytearray([reg, (addr >> 8) & 0xFF, addr & 0xFF])
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buf = bytearray(length)
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while not self.spi_device.try_lock():
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pass
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self._cs.value = False
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self.spi_device.write(cmd)
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self.spi_device.readinto(buf)
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self._cs.value = True
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self.spi_device.unlock()
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return buf
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def read8(self, addr, reg=SRAM_READ):
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return self.read(addr, 1, reg)[0]
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def read16(self, addr, reg=SRAM_READ):
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buf = self.read(addr, 2, reg)
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return buf[0] << 8 | buf[1]
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def write8(self, addr, value, reg=SRAM_WRITE):
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self.write(addr, [value], reg)
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def write16(self, addr, value, reg=SRAM_WRITE):
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self.write(addr, [value >> 8, value], reg)
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def erase(self, addr, length, value):
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cmd = bytearray([Adafruit_MCP_SRAM.SRAM_WRITE, (addr >> 8) & 0xFF, addr & 0xFF])
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while not self.spi_device.try_lock():
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pass
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self._cs.value = False
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self.spi_device.write(cmd)
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for x in range(length):
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self.spi_device.write(bytearray([value]))
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self._cs.value = True
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self.spi_device.unlock()
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