From 67e3171da05c54d217514e2541d70eec07909a9b Mon Sep 17 00:00:00 2001 From: Peter Harper Date: Fri, 26 Jan 2024 16:26:08 +0000 Subject: [PATCH] Add an example of using using DMA with PIO Fixes #467 --- README.md | 1 + pio/CMakeLists.txt | 1 + pio/uart_pio_dma/CMakeLists.txt | 11 ++ pio/uart_pio_dma/uart_pio_dma.c | 312 ++++++++++++++++++++++++++++++++ 4 files changed, 325 insertions(+) create mode 100644 pio/uart_pio_dma/CMakeLists.txt create mode 100644 pio/uart_pio_dma/uart_pio_dma.c diff --git a/README.md b/README.md index 1b693554a..a7b089b52 100644 --- a/README.md +++ b/README.md @@ -236,6 +236,7 @@ App|Description [uart_tx](pio/uart_tx) | Implement the transmit component of a UART serial port, and print hello world. [ws2812](pio/ws2812) | Examples of driving WS2812 addressable RGB LEDs. [addition](pio/addition) | Add two integers together using PIO. Only around 8 billion times slower than Cortex-M0+. +[uart_pio_dma](pio/uart_pio_dma) | Send and receive data from a UART implemented using the PIO and DMA ### PWM diff --git a/pio/CMakeLists.txt b/pio/CMakeLists.txt index 12fd67983..d35928418 100644 --- a/pio/CMakeLists.txt +++ b/pio/CMakeLists.txt @@ -19,4 +19,5 @@ if (NOT PICO_NO_HARDWARE) add_subdirectory(uart_rx) add_subdirectory(uart_tx) add_subdirectory(ws2812) + add_subdirectory(uart_pio_dma) endif () diff --git a/pio/uart_pio_dma/CMakeLists.txt b/pio/uart_pio_dma/CMakeLists.txt new file mode 100644 index 000000000..108477610 --- /dev/null +++ b/pio/uart_pio_dma/CMakeLists.txt @@ -0,0 +1,11 @@ +add_executable(uart_pio_dma) +pico_generate_pio_header(uart_pio_dma ${CMAKE_CURRENT_LIST_DIR}/../uart_rx/uart_rx.pio) +pico_generate_pio_header(uart_pio_dma ${CMAKE_CURRENT_LIST_DIR}/../uart_tx/uart_tx.pio) +target_sources(uart_pio_dma PRIVATE uart_pio_dma.c) +target_link_libraries(uart_pio_dma PRIVATE + pico_stdlib + hardware_pio + hardware_dma + ) +pico_add_extra_outputs(uart_pio_dma) +example_auto_set_url(uart_pio_dma) diff --git a/pio/uart_pio_dma/uart_pio_dma.c b/pio/uart_pio_dma/uart_pio_dma.c new file mode 100644 index 000000000..6a4c75ea6 --- /dev/null +++ b/pio/uart_pio_dma/uart_pio_dma.c @@ -0,0 +1,312 @@ +/** + * Copyright (c) 2024 Raspberry Pi (Trading) Ltd. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include +#include + +#include "pico/stdlib.h" +#include "hardware/pio.h" +#include "hardware/uart.h" +#include "hardware/dma.h" +#include "uart_rx.pio.h" +#include "uart_tx.pio.h" + +// Sends data via GPIO 4 and receives it on GPIO 5 +// Connect these pins with a wire +#define GPIO_TX 4 +#define GPIO_RX 5 + +#define SERIAL_BAUD 921600 +#define HARD_UART_INST uart1 + +#define USE_PIO_FOR_RX 1 +#define USE_DMA_FOR_RX 1 +#define USE_PIO_FOR_TX 1 +#define USE_DMA_FOR_TX 1 + +#ifndef DMA_IRQ_PRIORITY +#define DMA_IRQ_PRIORITY PICO_SHARED_IRQ_HANDLER_DEFAULT_ORDER_PRIORITY +#endif + +#ifndef PIO_IRQ_PRIORITY +#define PIO_IRQ_PRIORITY PICO_SHARED_IRQ_HANDLER_DEFAULT_ORDER_PRIORITY +#endif + +#define PIO_IRQ_NUM 0 +#define DMA_IRQ_NUM 0 + +#define DMA_IRQX(N) DMA_IRQ_ ## N +#define DMA_IRQN(N) DMA_IRQX(N) + +// dma channels +static uint dma_channel_rx; +static uint dma_channel_tx; + +// pio hardware +#if USE_PIO_FOR_RX +static PIO pio_hw_rx; +static uint pio_sm_rx; +static uint offset_rx; +#endif + +#if USE_PIO_FOR_TX +static PIO pio_hw_tx; +static uint pio_sm_tx; +static uint offset_tx; +#endif + +// read request size for progress +static uint32_t read_size; + +// PIO interrupt handler, called when the state machine fifo is not empty +// note: shouldn't printf in an irq normally! +static void pio_irq_handler() { + dma_channel_hw_t *dma_chan = dma_channel_hw_addr(dma_channel_rx); + printf("pio_rx dma_rx=%u/%u\n", read_size - dma_chan->transfer_count, read_size); +} + +// DMA interrupt handler, called when a DMA channel has transmitted its data +static void dma_irq_handler() { + if (dma_channel_tx >= 0 && dma_irqn_get_channel_status(DMA_IRQ_NUM, dma_channel_tx)) { + dma_irqn_acknowledge_channel(DMA_IRQ_NUM, dma_channel_tx); + printf("dma_tx done\n"); + } + if (dma_channel_rx >= 0 && dma_irqn_get_channel_status(DMA_IRQ_NUM, dma_channel_rx)) { + dma_irqn_acknowledge_channel(DMA_IRQ_NUM, dma_channel_rx); + printf("dma_rx done\n"); + } +} + +// Return a pointer to pio hardware +static PIO pio_hardware(int n) { + static_assert(NUM_PIOS == 2, ""); + const PIO pios[] = {pio0, pio1}; + return pios[n]; +} + +// Return irqn for the pio +static int pio_irqn(PIO pio_hw, int irqn) { + assert(irqn < (PIO1_IRQ_0 - PIO0_IRQ_0)); + return PIO0_IRQ_0 + (PIO1_IRQ_0 - PIO0_IRQ_0) * pio_get_index(pio_hw) + irqn; +} + +// Allocates a pio and statemachine and loads the pio program into memory +// Return true on success +static bool pio_claim_free_sm_add_program(const pio_program_t *program, PIO *pio_hw, uint *sm, uint *offset) { + // Find a free pio + int count = NUM_PIOS; + while(count--) { + *pio_hw = pio_hardware(count); + if (!pio_can_add_program(*pio_hw, program)) { + continue; + } + // Find a state machine + *sm = (int8_t)pio_claim_unused_sm(*pio_hw, false); + if (*sm < 0) { + continue; + } + *offset = pio_add_program(*pio_hw, program); + return true; + } + return false; +} + +// free up pio resources +static void pio_remove_program_unclaim_sm(const pio_program_t *program, PIO pio_hw, uint sm, uint offset) { + pio_remove_program(pio_hw, program, offset); + pio_sm_unclaim(pio_hw, sm); +} + +static void dump_bytes(const char *bptr, uint32_t len) { + unsigned int i = 0; + for (i = 0; i < len;) { + if ((i & 0x0f) == 0) { + printf("\n"); + } else if ((i & 0x07) == 0) { + printf(" "); + } + printf("%02x ", bptr[i++]); + } + printf("\n"); +} + +int main() +{ + setup_default_uart(); + + // setup text we are going to send and what we expect to get back + const char buffer_tx[] = "the quick brown fox jumps over the lazy dog"; + + // Buffer for receiving data + char buffer_rx[sizeof(buffer_tx) - 1] = {0}; + +#if !USE_PIO_FOR_RX || !USE_PIO_FOR_TX + uart_init(HARD_UART_INST, SERIAL_BAUD); +#endif + +// setup pio for rx +#if USE_PIO_FOR_RX + if (!pio_claim_free_sm_add_program(&uart_rx_mini_program, &pio_hw_rx, &pio_sm_rx, &offset_rx)) { + panic("failed to allocate pio for rx"); + } + uart_rx_mini_program_init(pio_hw_rx, pio_sm_rx, offset_rx, GPIO_RX, SERIAL_BAUD); +#else + gpio_set_function(GPIO_RX, GPIO_FUNC_UART); +#endif + +// setup pio for tx +#if USE_PIO_FOR_TX + if (!pio_claim_free_sm_add_program(&uart_tx_program, &pio_hw_tx, &pio_sm_tx, &offset_tx)) { + panic("failed to allocate pio for tx"); + } + uart_tx_program_init(pio_hw_tx, pio_sm_tx, offset_tx, GPIO_TX, SERIAL_BAUD); +#else + gpio_set_function(GPIO_TX, GPIO_FUNC_UART); +#endif + +// setup pio interrupt +#if USE_PIO_FOR_RX + if (irq_get_exclusive_handler(pio_irqn(pio_hw_rx, PIO_IRQ_NUM))) { + panic("PIO IRQ in use"); + } +#if USE_DMA_FOR_RX + irq_add_shared_handler(pio_irqn(pio_hw_rx, PIO_IRQ_NUM), pio_irq_handler, PIO_IRQ_PRIORITY); + pio_set_irqn_source_enabled(pio_hw_rx, PIO_IRQ_NUM, pis_sm0_rx_fifo_not_empty + pio_sm_rx, true); + irq_set_enabled(pio_irqn(pio_hw_rx, PIO_IRQ_NUM), true); +#endif +#endif + +// add dma handler +#if USE_DMA_FOR_RX || USE_DMA_FOR_TX + if (irq_get_exclusive_handler(DMA_IRQN(DMA_IRQ_NUM))) { + panic("DMA IRQ in use"); + } + irq_add_shared_handler(DMA_IRQN(DMA_IRQ_NUM), dma_irq_handler, DMA_IRQ_PRIORITY); + irq_set_enabled(DMA_IRQN(DMA_IRQ_NUM), true); +#endif + +// Setup dma for read +#if USE_DMA_FOR_RX + dma_channel_rx = dma_claim_unused_channel(false); + if (dma_channel_rx < 0) { + panic("No free dma channels"); + } + dma_channel_config config_rx = dma_channel_get_default_config(dma_channel_rx); + channel_config_set_transfer_data_size(&config_rx, DMA_SIZE_8); + channel_config_set_read_increment(&config_rx, false); + channel_config_set_write_increment(&config_rx, true); + read_size = sizeof(buffer_tx) - 1; + // enable irq for rx + dma_irqn_set_channel_enabled(DMA_IRQ_NUM, dma_channel_rx, true); +#if USE_PIO_FOR_RX + // read from pio fifo + channel_config_set_dreq(&config_rx, pio_get_dreq(pio_hw_rx, pio_sm_rx, false)); + // 8-bit read from the uppermost byte of the FIFO, as data is left-justified so need to add 3. Don't forget the cast! + dma_channel_configure(dma_channel_rx, &config_rx, buffer_rx, (io_rw_8*)&pio_hw_rx->rxf[pio_sm_rx] + 3, read_size, true); // dma started +#else + // read from uart hardware + channel_config_set_dreq(&config_rx, uart_get_dreq(HARD_UART_INST, false)); + dma_channel_configure(dma_channel_rx, &config_rx, buffer_rx, &uart_get_hw(HARD_UART_INST)->dr, read_size, true); // dma started +#endif +#endif + +// setup dma for write +#if USE_DMA_FOR_TX + dma_channel_tx = dma_claim_unused_channel(false); + if (dma_channel_tx < 0) { + panic("No free dma channels"); + } + dma_channel_config config_tx = dma_channel_get_default_config(dma_channel_tx); + channel_config_set_transfer_data_size(&config_tx, DMA_SIZE_8); + channel_config_set_read_increment(&config_tx, true); + channel_config_set_write_increment(&config_tx, false); + // enable irq for tx + dma_irqn_set_channel_enabled(DMA_IRQ_NUM, dma_channel_tx, true); +#if USE_PIO_FOR_RX + // write to pio fifo + channel_config_set_dreq(&config_tx, pio_get_dreq(pio_hw_tx, pio_sm_tx, true)); + dma_channel_configure(dma_channel_tx, &config_tx, &pio_hw_rx->txf[pio_sm_tx], buffer_tx, sizeof(buffer_tx) - 1, true); // dma started +#else + // write to uart hardware + channel_config_set_dreq(&config_tx, uart_get_dreq(HARD_UART_INST, true)); + dma_channel_configure(dma_channel_tx, &config_tx, &uart_get_hw(HARD_UART_INST)->dr, buffer_tx, sizeof(buffer_tx) - 1, true); // dma started +#endif +#endif + +// send data +#if USE_DMA_FOR_TX + dma_channel_wait_for_finish_blocking(dma_channel_tx); // wait for tx +#elif USE_PIO_FOR_TX + // write to the pio fifo + int count_pio_tx = 0; + while(count_pio_tx < sizeof(buffer_tx) - 1) { + uart_tx_program_putc(pio_hw_tx, pio_sm_tx, buffer_tx[count_pio_tx++]); + } +#else + uart_puts(HARD_UART_INST, buffer_tx); +#endif + +// Receive the data +#if USE_DMA_FOR_RX + // wait for dma rx + dma_channel_wait_for_finish_blocking(dma_channel_rx); +#elif USE_PIO_FOR_RX + // read from the pio fifo + int count_pio_rx = 0; + while(count_pio_rx < sizeof(buffer_tx) - 1) { + buffer_rx[count_pio_rx++] = uart_rx_program_getc(pio_hw_rx, pio_sm_rx); + } +#else + // use the uart hardware + int count_uart_rx = 0; + while(count_uart_rx < sizeof(buffer_tx) - 1) { + buffer_rx[count_uart_rx++] = uart_getc(HARD_UART_INST); + } +#endif + + // check + if (memcmp(buffer_rx, buffer_tx, sizeof(buffer_tx) - 1) == 0) { + printf("Test passed\n"); + } else { + printf("buffer_tx: >%s<\n", buffer_tx); + dump_bytes(buffer_tx, sizeof(buffer_tx)); + printf("result: >%s<\n", buffer_rx); + dump_bytes(buffer_rx, sizeof(buffer_rx)); + printf("Test failed\n"); + assert(0); + } + + // cleanup +#if USE_DMA_FOR_TX + dma_irqn_set_channel_enabled(DMA_IRQ_NUM, dma_channel_tx, false); + dma_channel_unclaim(dma_channel_tx); +#endif +#if USE_DMA_FOR_RX + dma_irqn_set_channel_enabled(DMA_IRQ_NUM, dma_channel_rx, false); + dma_channel_unclaim(dma_channel_rx); +#endif +#if USE_DMA_FOR_RX || USE_DMA_FOR_TX + irq_remove_handler(DMA_IRQN(DMA_IRQ_NUM), dma_irq_handler); + if (!irq_has_shared_handler(DMA_IRQN(DMA_IRQ_NUM))) { + irq_set_enabled(DMA_IRQN(DMA_IRQ_NUM), false); + } +#endif +#if USE_PIO_FOR_RX + pio_set_irqn_source_enabled(pio_hw_rx, PIO_IRQ_NUM, pis_sm0_rx_fifo_not_empty + pio_sm_rx, false); + irq_remove_handler(pio_irqn(pio_hw_rx, PIO_IRQ_NUM), pio_irq_handler); + if (!irq_has_shared_handler(pio_irqn(pio_hw_rx, PIO_IRQ_NUM))) { + irq_set_enabled(pio_irqn(pio_hw_rx, PIO_IRQ_NUM), false); + } + pio_remove_program_unclaim_sm(&uart_rx_mini_program, pio_hw_rx, pio_sm_rx, offset_rx); +#endif +#if USE_PIO_FOR_TX + pio_remove_program_unclaim_sm(&uart_tx_program, pio_hw_tx, pio_sm_tx, offset_tx); +#endif +#if !USE_PIO_FOR_RX || !USE_PIO_FOR_TX + uart_deinit(HARD_UART_INST); +#endif + return 0; +}