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Support for CS active high #258

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Support for CS active high #258

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c93e1e7
Support for CS active high
tfnil Jul 7, 2021
2178afa
Improved handling of CS active high
tfnil Jul 10, 2021
747c313
BUgfix: handle several CS lines properly
tfnil Jul 10, 2021
5e3a7e1
SPI: better API for CS active high
tfnil Aug 24, 2021
775dd18
SPI: fix unit test for CS active high
tfnil Aug 25, 2021
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21 changes: 17 additions & 4 deletions pyftdi/spi.py
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Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,10 @@ def set_mode(self, mode: int, cs_hold: Optional[int] = None) -> None:
self._cpha = bool(mode & 0x1)
cs_clock = 0xFF & ~((int(not self._cpol) and SpiController.SCK_BIT) |
SpiController.DO_BIT)
cs_select = 0xFF & ~((SpiController.CS_BIT << self._cs) |
cs_bit_sel = ~((self._controller._cs_idle
^ (SpiController.CS_BIT << self._cs))
& self._controller._cs_bits)
cs_select = 0xFF & ~(cs_bit_sel |
(int(not self._cpol) and SpiController.SCK_BIT) |
SpiController.DO_BIT)
self._cs_prolog = bytes([cs_clock, cs_select])
Expand Down Expand Up @@ -355,6 +358,8 @@ def __init__(self, cs_count: int = 1, turbo: bool = True):
self._frequency = 0.0
self._clock_phase = False
self._cs_bits = 0
self._cs_idle = 0
self._cs_act_hi = 0
self._spi_ports = []
self._spi_dir = 0
self._spi_mask = self.SPI_BITS
Expand Down Expand Up @@ -384,6 +389,9 @@ def configure(self, url: Union[str, UsbDevice],
frequency.
* ``cs_count`` count of chip select signals dedicated to select
SPI slave devices, starting from A*BUS3 pin
* ``cs_act_hi`` a bitfield specifying which SPI CS lines are active
high. Bit 4 is the first CS, bit 5 the second and so on. Bits
corresponding to pins not used/configured as CS are ignored.
* ``turbo`` whether to enable or disable turbo mode
* ``debug`` to increase log verbosity, using MPSSE tracer
"""
Expand All @@ -396,6 +404,9 @@ def configure(self, url: Union[str, UsbDevice],
if not 1 <= self._cs_count <= 5:
raise ValueError('Unsupported CS line count: %d' %
self._cs_count)
if 'cs_act_hi' in kwargs:
self._cs_act_hi = int(kwargs['cs_act_hi'])
del kwargs['cs_act_hi']
if 'turbo' in kwargs:
self._turbo = bool(kwargs['turbo'])
del kwargs['turbo']
Expand All @@ -421,6 +432,8 @@ def configure(self, url: Union[str, UsbDevice],
raise SpiIOError('Already configured')
self._cs_bits = (((SpiController.CS_BIT << self._cs_count) - 1) &
~(SpiController.CS_BIT - 1))
self._cs_act_hi &= self._cs_bits
self._cs_idle = (~self._cs_act_hi) & self._cs_bits
self._spi_ports = [None] * self._cs_count
self._spi_dir = (self._cs_bits |
SpiController.DO_BIT |
Expand All @@ -431,7 +444,7 @@ def configure(self, url: Union[str, UsbDevice],
# delay any truncation till the device is actually open
self._set_gpio_direction(16, (~self._spi_mask) & 0xFFFF, io_dir)
kwargs['direction'] = self._spi_dir | self._gpio_dir
kwargs['initial'] = self._cs_bits | (io_out & self._gpio_mask)
kwargs['initial'] = self._cs_idle | (io_out & self._gpio_mask)
if not isinstance(url, str):
self._frequency = self._ftdi.open_mpsse_from_device(
url, interface=interface, **kwargs)
Expand Down Expand Up @@ -800,7 +813,7 @@ def _exchange_half_duplex(self, frequency: float,
ctrl |= self._gpio_low
epilog.extend((Ftdi.SET_BITS_LOW, ctrl, direction))
# Restore idle state
cs_high = [Ftdi.SET_BITS_LOW, self._cs_bits | self._gpio_low,
cs_high = [Ftdi.SET_BITS_LOW, self._cs_idle | self._gpio_low,
direction]
if not self._turbo:
cs_high.append(Ftdi.SEND_IMMEDIATE)
Expand Down Expand Up @@ -907,7 +920,7 @@ def _exchange_full_duplex(self, frequency: float,
ctrl |= self._gpio_low
epilog.extend((Ftdi.SET_BITS_LOW, ctrl, direction))
# Restore idle state
cs_high = [Ftdi.SET_BITS_LOW, self._cs_bits | self._gpio_low,
cs_high = [Ftdi.SET_BITS_LOW, self._cs_idle | self._gpio_low,
direction]
if not self._turbo:
cs_high.append(Ftdi.SEND_IMMEDIATE)
Expand Down