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pico-uart-bridge/uart-bridge.c
Andrew J. Kroll cc42c66af4 Fix ISRs, and USB descripters
2024-04-14 19:36:53 -04:00

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// SPDX-License-Identifier: MIT
/*
* Copyright 2021 Álvaro Fernández Rojas <noltari@gmail.com>
* Cleanup/modifications Copyright 2023 Andrew J. Kroll <xxxajk at gmail>
*
*/
#include <hardware/irq.h>
#include <hardware/structs/sio.h>
#include <hardware/uart.h>
#include <pico/multicore.h>
#include <pico/stdlib.h>
#include <string.h>
#include <tusb.h>
#if !defined(MIN)
#define MIN(a, b) ((a > b) ? b : a)
#endif /* MIN */
#define SYS_LED_ACTIVE 25
#define BUFFER_SIZE 2560
#define LED_TIMEOUT 10
#define UART0_TX 0
#define UART0_RX 1
#define UART0_LED_TX 19 // not used for UDPI
#define UART0_LED_RX 18
#define UART1_TX 4
#define UART1_RX 5
#define UART1_LED_TX 17
#define UART1_LED_RX 16
#define DEF_BIT_RATE 115200
#define DEF_STOP_BITS 1
#define DEF_PARITY 0
#define DEF_DATA_BITS 8
typedef struct {
uart_inst_t * const inst;
uint irq;
void *irq_fn;
uint8_t tx_pin;
uint8_t rx_pin;
uint8_t tx_led;
uint8_t rx_led;
} uart_id_t;
typedef struct {
cdc_line_coding_t usb_lc;
cdc_line_coding_t uart_lc;
mutex_t lc_mtx;
uint8_t uart_buffer[BUFFER_SIZE];
uint32_t uart_pos;
mutex_t uart_mtx;
uint8_t usb_buffer[BUFFER_SIZE];
uint32_t usb_pos;
mutex_t usb_mtx;
volatile uint8_t countdown_LED_TX;
volatile uint8_t countdown_LED_RX;
critical_section_t spinlock_LED_TX;
critical_section_t spinlock_LED_RX;
} uart_data_t;
void uart0_irq_fn(void);
void uart1_irq_fn(void);
const uart_id_t UART_ID[CFG_TUD_CDC] = {
{
.inst = uart0,
.irq = UART0_IRQ,
.irq_fn = &uart0_irq_fn,
.tx_pin = UART0_TX,
.rx_pin = UART0_RX,
.tx_led = UART0_LED_TX,
.rx_led = UART0_LED_RX,
},
{
.inst = uart1,
.irq = UART1_IRQ,
.irq_fn = &uart1_irq_fn,
.tx_pin = UART1_TX,
.rx_pin = UART1_RX,
.tx_led = UART1_LED_TX,
.rx_led = UART1_LED_RX,
}
};
uart_data_t UART_DATA[CFG_TUD_CDC];
struct repeating_timer stimulate;
volatile bool ready = false;
void init_led(uint8_t p) {
gpio_init(p);
gpio_set_dir(p, GPIO_OUT);
gpio_put(p, 0);
}
static inline uint databits_usb2uart(uint8_t data_bits) {
switch(data_bits) {
case 5:
return 5;
case 6:
return 6;
case 7:
return 7;
default:
return 8;
}
}
static inline uart_parity_t parity_usb2uart(uint8_t usb_parity) {
switch(usb_parity) {
case 1:
return UART_PARITY_ODD;
case 2:
return UART_PARITY_EVEN;
default:
return UART_PARITY_NONE;
}
}
static inline uint stopbits_usb2uart(uint8_t stop_bits) {
switch(stop_bits) {
case 2:
return 2;
default:
return 1;
}
}
void update_uart_cfg(uint8_t itf) {
const uart_id_t *ui = &UART_ID[itf];
uart_data_t *ud = &UART_DATA[itf];
mutex_enter_blocking(&ud->lc_mtx);
if(ud->usb_lc.bit_rate != ud->uart_lc.bit_rate) {
uart_set_baudrate(ui->inst, ud->usb_lc.bit_rate);
ud->uart_lc.bit_rate = ud->usb_lc.bit_rate;
}
if((ud->usb_lc.stop_bits != ud->uart_lc.stop_bits) || (ud->usb_lc.parity != ud->uart_lc.parity) || (ud->usb_lc.data_bits != ud->uart_lc.data_bits)) {
uart_set_format(ui->inst, databits_usb2uart(ud->usb_lc.data_bits), stopbits_usb2uart(ud->usb_lc.stop_bits), parity_usb2uart(ud->usb_lc.parity));
ud->uart_lc.data_bits = ud->usb_lc.data_bits;
ud->uart_lc.parity = ud->usb_lc.parity;
ud->uart_lc.stop_bits = ud->usb_lc.stop_bits;
}
mutex_exit(&ud->lc_mtx);
}
void usb_read_bytes(uint8_t itf) {
uart_data_t *ud = &UART_DATA[itf];
uint32_t len = tud_cdc_n_available(itf);
if(len && mutex_try_enter(&ud->usb_mtx, NULL)) {
len = MIN(len, BUFFER_SIZE - ud->usb_pos);
if(len) {
uint32_t count;
count = tud_cdc_n_read(itf, &ud->usb_buffer[ud->usb_pos], len);
ud->usb_pos += count;
}
mutex_exit(&ud->usb_mtx);
}
}
void usb_write_bytes(uint8_t itf) {
uart_data_t *ud = &UART_DATA[itf];
if(ud->uart_pos) {
if(mutex_try_enter(&ud->uart_mtx, NULL)) {
uint32_t count = tud_cdc_n_write(itf, ud->uart_buffer, ud->uart_pos);
// horrible! should use ring buffers!!
if(count < ud->uart_pos) {
memmove(ud->uart_buffer, &ud->uart_buffer[count], ud->uart_pos - count);
}
ud->uart_pos -= count;
mutex_exit(&ud->uart_mtx);
if(count)
tud_cdc_n_write_flush(itf);
}
}
}
void tud_cdc_send_break_cb(uint8_t itf, uint16_t duration_ms) {
const uart_id_t *ui = &UART_ID[itf];
uart_data_t *ud = &UART_DATA[itf];
// is mutex for tx even needed??
//mutex_enter_blocking(&ud->lc_mtx);
if(duration_ms == 0xffff) {
uart_set_break(ui->inst, true);
} else if(duration_ms == 0x0000) {
uart_set_break(ui->inst, false);
} else {
// should be correct for non-compliant stacks?
uart_set_break(ui->inst, true);
sleep_ms(duration_ms);
uart_set_break(ui->inst, false);
}
//mutex_exit(&ud->lc_mtx);
}
void usb_cdc_process(uint8_t itf) {
uart_data_t *ud = &UART_DATA[itf];
mutex_enter_blocking(&ud->lc_mtx);
tud_cdc_n_get_line_coding(itf, &ud->usb_lc);
mutex_exit(&ud->lc_mtx);
usb_read_bytes(itf);
usb_write_bytes(itf);
}
void core1_entry(void) {
tusb_init();
ready = true;
while(1) {
int itf;
tud_task();
if(tud_ready()) { // we need to ignore DTR on the CDC side
gpio_put(SYS_LED_ACTIVE, 1);
for(itf = 0; itf < CFG_TUD_CDC; itf++) {
usb_cdc_process(itf);
}
} else {
gpio_put(SYS_LED_ACTIVE, 0);
}
}
}
void stimulate_status(uint8_t itf) {
const uart_id_t *ui = &UART_ID[itf];
uart_data_t *ud = &UART_DATA[itf];
critical_section_enter_blocking(&ud->spinlock_LED_RX);
if(ud->countdown_LED_RX == LED_TIMEOUT) {
gpio_put(ui->rx_led, 1);
}
if(ud->countdown_LED_RX != 0) {
ud->countdown_LED_RX--;
if(ud->countdown_LED_RX == 0) {
gpio_put(ui->rx_led, 0);
}
}
critical_section_exit(&ud->spinlock_LED_RX);
critical_section_enter_blocking(&ud->spinlock_LED_TX);
if(ud->countdown_LED_TX == LED_TIMEOUT) {
gpio_put(ui->tx_led, 1);
}
if(ud->countdown_LED_TX != 0) {
ud->countdown_LED_TX--;
if(ud->countdown_LED_TX == 0) {
gpio_put(ui->tx_led, 0);
}
}
critical_section_exit(&ud->spinlock_LED_TX);
}
bool update_status(struct repeating_timer *t) {
for(uint8_t itf = 0; itf < CFG_TUD_CDC; itf++) {
stimulate_status(itf);
}
return true;
}
static inline void uart_read_bytes(uint8_t itf) {
uart_data_t *ud = &UART_DATA[itf];
const uart_id_t *ui = &UART_ID[itf];
if(uart_is_readable(ui->inst)) {
critical_section_enter_blocking(&ud->spinlock_LED_RX);
ud->countdown_LED_RX = LED_TIMEOUT;
critical_section_exit(&ud->spinlock_LED_RX);
mutex_enter_blocking(&ud->uart_mtx);
if(ud->uart_pos < BUFFER_SIZE) {
ud->uart_buffer[ud->uart_pos] = uart_getc(ui->inst);
ud->uart_pos++;
} else {
uart_getc(ui->inst); // drop it on the floor
}
mutex_exit(&ud->uart_mtx);
}
}
void uart_write_bytes(uint8_t itf) {
uart_data_t *ud = &UART_DATA[itf];
if(ud->usb_pos && mutex_try_enter(&ud->usb_mtx, NULL)) {
const uart_id_t *ui = &UART_ID[itf];
// horrible! should use ring buffers!!
if(uart_is_writable(ui->inst)) { // && count < ud->usb_pos) {
critical_section_enter_blocking(&ud->spinlock_LED_TX);
ud->countdown_LED_TX = LED_TIMEOUT;
critical_section_exit(&ud->spinlock_LED_TX);
uart_putc_raw(ui->inst, ud->usb_buffer[0]);
if(ud->usb_pos > 1) {
memmove(ud->usb_buffer, &ud->usb_buffer[1], ud->usb_pos - 1);
}
ud->usb_pos--;
}
mutex_exit(&ud->usb_mtx);
}
}
void uart0_irq_fn(void) {
uart_read_bytes(0);
}
void uart1_irq_fn(void) {
uart_read_bytes(1);
}
void init_uart_data(uint8_t itf) {
const uart_id_t *ui = &UART_ID[itf];
uart_data_t *ud = &UART_DATA[itf];
init_led(ui->tx_led);
init_led(ui->rx_led);
ud->countdown_LED_TX = 0;
ud->countdown_LED_RX = 0;
critical_section_init(&ud->spinlock_LED_TX);
critical_section_init(&ud->spinlock_LED_RX);
/* Pinmux */
gpio_set_function(ui->tx_pin, GPIO_FUNC_UART);
gpio_set_function(ui->rx_pin, GPIO_FUNC_UART);
gpio_pull_up(ui->rx_pin); // important missed detail, prevents connection glitches
/* USB CDC LC */
ud->usb_lc.bit_rate = DEF_BIT_RATE;
ud->usb_lc.data_bits = DEF_DATA_BITS;
ud->usb_lc.parity = DEF_PARITY;
ud->usb_lc.stop_bits = DEF_STOP_BITS;
/* UART LC */
ud->uart_lc.bit_rate = DEF_BIT_RATE;
ud->uart_lc.data_bits = DEF_DATA_BITS;
ud->uart_lc.parity = DEF_PARITY;
ud->uart_lc.stop_bits = DEF_STOP_BITS;
/* Buffer */
ud->uart_pos = 0;
ud->usb_pos = 0;
/* Mutex */
mutex_init(&ud->lc_mtx);
mutex_init(&ud->uart_mtx);
mutex_init(&ud->usb_mtx);
/* UART start */
uart_init(ui->inst, ud->usb_lc.bit_rate);
uart_set_hw_flow(ui->inst, false, false);
uart_set_format(ui->inst, databits_usb2uart(ud->usb_lc.data_bits),
stopbits_usb2uart(ud->usb_lc.stop_bits),
parity_usb2uart(ud->usb_lc.parity));
uart_set_fifo_enabled(ui->inst, false);
uart_set_translate_crlf(ui->inst, false);
/* UART RX Interrupt */
irq_set_exclusive_handler(ui->irq, ui->irq_fn);
}
void start_uarts() {
uint8_t itf;
for(itf = 0; itf < CFG_TUD_CDC; itf++) {
init_uart_data(itf);
}
// init led stimulator
add_repeating_timer_ms(1, update_status, NULL, &stimulate);
// enable ISRs
for(itf = 0; itf < CFG_TUD_CDC; itf++) {
const uart_id_t *ui = &UART_ID[itf];
irq_set_enabled(ui->irq, true);
uart_set_irq_enables(ui->inst, true, false);
}
}
int main(void) {
int itf;
set_sys_clock_khz(125000, false);
multicore_reset_core1();
init_led(SYS_LED_ACTIVE);
usbd_serial_init();
start_uarts();
multicore_launch_core1(core1_entry);
do {
sleep_us(1);
} while(!ready);
while(1) {
if(tud_ready()) {
for(itf = 0; itf < CFG_TUD_CDC; itf++) {
update_uart_cfg(itf);
uart_write_bytes(itf);
}
}
}
return 0;
}
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