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mjlyons |
from cheetah_py import *
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class SpiComm:
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"""Controls a Cheetah USB/SPI adapter to talk over SPI to the spiifc
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module"""
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_port = 0 # Change if using multiple Cheetahs
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_mode = 3 # spiifc SPI mode
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handle = None # handle to Cheetah SPI
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class SpiCommError(Exception):
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"""There was some error interacting with the Cheetah SPI adapter"""
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def __init__(self, msg):
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self.msg = msg
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def __init__(self, kbpsBitrate=9000):
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self.handle = ch_open(self._port)
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if (self.handle <= 0):
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raise SpiCommError("Unable to open Cheetah device on port %d.\nError code = %d (%s)" % (self._port, self.handle, ch_status_string(self.handle)))
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ch_host_ifce_speed(self.handle)
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ch_spi_configure(self.handle, (self._mode >> 1), self._mode & 1,
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CH_SPI_BITORDER_MSB, 0x0)
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ch_spi_bitrate(self.handle, kbpsBitrate)
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def __del__(self):
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ch_close(self.handle)
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def SendToSlave(self, byteArray):
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byteCount = len(byteArray) + 1
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data_in = array('B', [0 for i in range(byteCount)])
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actualByteCount = 0
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ch_spi_queue_clear(self.handle)
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ch_spi_queue_oe(self.handle, 1)
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ch_spi_queue_ss(self.handle, 0x1)
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for byte in byteArray:
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ch_spi_queue_byte(self.handle, 1, byte)
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ch_spi_queue_ss(self.handle, 0)
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ch_spi_queue_oe(self.handle, 0)
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(actualByteCount, data_in) = ch_spi_batch_shift(self.handle, byteCount)
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def RecvFromSlave(self, command, byteCount):
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totalByteCount = byteCount + 1 # Extra byte for cmd
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data_in = array('B', [0 for i in range(totalByteCount)])
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actualByteCount = 0
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ch_spi_queue_clear(self.handle)
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ch_spi_queue_oe(self.handle, 1)
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ch_spi_queue_ss(self.handle, 1)
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ch_spi_queue_byte(self.handle, 1, command) # Receive data from slave
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ch_spi_queue_byte(self.handle, byteCount, 0xFF)
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ch_spi_queue_ss(self.handle, 0x0)
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ch_spi_queue_oe(self.handle, 0)
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(actualByteCount, data_in) = ch_spi_batch_shift(self.handle,
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totalByteCount)
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return data_in[1:]
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def ReadMemory(self, byteCount):
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return self.RecvFromSlave(0x3, byteCount)
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def WriteMemory(self, bytesToWrite):
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bytePacket = [0x01]
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bytePacket.extend(bytesToWrite)
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return self.SendToSlave(bytePacket)
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def ReadReg(self, regId):
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commandCode = 0x80 + regId
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regValBytes = self.RecvFromSlave(commandCode, 4)
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regValWord = 0
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for regValByte in regValBytes:
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regValWord = (regValWord * 256) + regValByte
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return regValWord
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def WriteReg(self, regId, value):
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commandCode = 0xC0 + regId
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bytesToSend = [commandCode, 0, 0, 0, 0]
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for sendByteId in range(4,0,-1):
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bytesToSend[sendByteId] = value % 256
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value = value / 256
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self.SendToSlave(bytesToSend)
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