f45412793e
This class supports SPI bus controller mode, with blocking transfers. SPI device numbers start at 0, to comply with the pinout of the Teensy boards. With the configured clock frequency the fastest baud rate is 33MHz. For messages longer 16 bytes DMA is used. The class uses the existing framework with extmod/machine_spi.c. Extended driver options: - drive=n with n being between 1 and 6 or PIN.POWER_1 to PIN.POWER_6. Since the pins used by the SPI are fixed, no Pin settings can be made. Thus the drive option is added allowing to control ringing and crosstalk on the connection. - gap_ns=nnnnn is the time between sent data items in a frame given in ns. Default is 2 clock cycles.
52 lines
2.1 KiB
C
52 lines
2.1 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2021 Robert Hammelrath
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "dma_channel.h"
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// List of channel flags: true: channel used, false: channel available
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static bool channel_list[32] = { true, true, true, true, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false,
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false, false, false, false, false, false, false, false };
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// allocate_channel(): retrieve an available channel. Return the number or -1
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int allocate_dma_channel(void) {
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for (int i = 0; i < ARRAY_SIZE(channel_list); i++) {
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if (channel_list[i] == false) { // Channel available
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channel_list[i] = true;
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return i;
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}
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}
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return -1;
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}
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// free_channel(n): Declare channel as free
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void free_dma_channel(int n) {
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if (n >= 0 && n <= ARRAY_SIZE(channel_list)) {
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channel_list[n] = false;
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}
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}
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