118 lines
4.8 KiB
Plaintext
118 lines
4.8 KiB
Plaintext
/*
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ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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* @defgroup UART UART Driver
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* @brief Generic UART Driver.
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* @details This driver abstracts a generic UART (Universal Asynchronous
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* Receiver Transmitter) peripheral, the API is designed to be:
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* - Unbuffered and copy-less, transfers are always directly performed
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* from/to the application-level buffers without extra copy
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* operations.
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* - Asynchronous, the API is always non blocking.
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* - Callbacks capable, operations completion and other events are
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* notified using callbacks.
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* .
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* Special hardware features like deep hardware buffers, DMA transfers
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* are hidden to the user but fully supportable by the low level
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* implementations.<br>
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* This driver model is best used where communication events are
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* meant to drive an higher level state machine, as example:
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* - RS485 drivers.
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* - Multipoint network drivers.
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* - Serial protocol decoders.
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* .
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* If your application requires a synchronous buffered driver then
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* the @ref SERIAL should be used instead.
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* @pre In order to use the UART driver the @p HAL_USE_UART option
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* must be enabled in @p halconf.h.
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*
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* @section uart_1 Driver State Machine
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* The driver implements a state machine internally, not all the driver
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* functionalities can be used in any moment, any transition not explicitly
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* shown in the following diagram has to be considered an error and shall
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* be captured by an assertion (if enabled).
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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uninit [label="UART_UNINIT", style="bold"];
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stop [label="UART_STOP\nLow Power"];
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ready [label="UART_READY\nClock Enabled"];
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uninit -> stop [label="\nuartInit()"];
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stop -> ready [label="\nuartStart()"];
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ready -> ready [label="\nuartStart()"];
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ready -> stop [label="\nuartStop()"];
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stop -> stop [label="\nuartStop()"];
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}
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* @enddot
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*
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* @subsection uart_1_1 Transmitter sub State Machine
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* The follow diagram describes the transmitter state machine, this diagram
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* is valid while the driver is in the @p UART_READY state. This state
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* machine is automatically reset to the @p TX_IDLE state each time the
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* driver enters the @p UART_READY state.
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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tx_idle [label="TX_IDLE", style="bold"];
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tx_active [label="TX_ACTIVE"];
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tx_complete [label="TX_COMPLETE"];
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tx_idle -> tx_active [label="\nuartStartSend()"];
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tx_idle -> tx_idle [label="\nuartStopSend()\n>txend2_cb<"];
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tx_active -> tx_complete [label="\nbuffer transmitted\n>txend1_cb<"];
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tx_active -> tx_idle [label="\nuartStopSend()"];
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tx_complete -> tx_active [label="\nuartStartSendI()\nthen\ncallback return"];
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tx_complete -> tx_idle [label="\ncallback return"];
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}
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* @enddot
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*
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* @subsection uart_1_2 Receiver sub State Machine
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* The follow diagram describes the receiver state machine, this diagram
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* is valid while the driver is in the @p UART_READY state. This state
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* machine is automatically reset to the @p RX_IDLE state each time the
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* driver enters the @p UART_READY state.
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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rx_idle [label="RX_IDLE", style="bold"];
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rx_active [label="RX_ACTIVE"];
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rx_complete [label="RX_COMPLETE"];
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rx_idle -> rx_idle [label="\nuartStopReceive()\n>rxchar_cb<\n>rxerr_cb<"];
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rx_idle -> rx_active [label="\nuartStartReceive()"];
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rx_active -> rx_complete [label="\nbuffer filled\n>rxend_cb<"];
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rx_active -> rx_idle [label="\nuartStopReceive()"];
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rx_active -> rx_active [label="\nreceive error\n>rxerr_cb<"];
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rx_complete -> rx_active [label="\nuartStartReceiveI()"];
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rx_complete -> rx_idle [label="\ncallback return"];
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}
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* @enddot
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*
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* @ingroup HAL_NORMAL_DRIVERS
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*/
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