hw/mcu/dialog: Disconnect UART RX pin it stays low
When UART RX pin is shorted to ground and UART is enabled it enters
busy state.
In this state busy interrupt fires constantly it prevents non-interrupt code
to be executed and can lead to watchdog reboot.
In function hal_uart_config() pullup was added to RX pin to enable configuration
(which was not successful in busy state).
This counter measure worked fined when RX pin was floating and just happen to be
low for a while but internal pull-up resistor was enough to make is stable.
However when RX pin is shorted to ground internal pull-up will not solve the problem.
- now RX pin is not routed to UART during configuration to prevent busy state at that time.
- RX can be disconnected from UART once it enters busy state, pin is reconfigured for
GPIO with interrupt to detect end of short condition. (This functionality is optionall
and can be enabled with syscfg value MCU_UART_DICONNECT_RX_ON_BUSY).
diff --git a/hw/mcu/dialog/da1469x/src/hal_uart.c b/hw/mcu/dialog/da1469x/src/hal_uart.c
index 0ce4e77..c0f810e 100644
--- a/hw/mcu/dialog/da1469x/src/hal_uart.c
+++ b/hw/mcu/dialog/da1469x/src/hal_uart.c
@@ -25,6 +25,7 @@
#include "mcu/da1469x_hal.h"
#include "mcu/mcu.h"
#include "hal/hal_uart.h"
+#include "hal/hal_gpio.h"
#include "defs/error.h"
#include "os/os_trace_api.h"
#include "os/util.h"
@@ -38,6 +39,8 @@
volatile uint8_t rx_stalled : 1;
volatile uint8_t tx_started : 1;
+ /* RX temporarily switched to GPIO with interrupt */
+ volatile uint8_t rx_disconnected : 1;
volatile uint8_t rx_data;
/*
@@ -150,6 +153,26 @@
uart->regs->UART2_IER_DLH_REG &= ~UART2_UART2_IER_DLH_REG_ERBFI_DLH0_Msk;
}
+static void
+da1469x_uart_set_rx_pin(struct da1469x_uart *uart)
+{
+ int mode = uart->cfg->rx_pullup ? MCU_GPIO_MODE_INPUT_PULLUP : MCU_GPIO_MODE_INPUT;
+
+ if (uart->cfg->pin_rx >= 0) {
+ mcu_gpio_set_pin_function(uart->cfg->pin_rx, mode, uart->rx_pin_func);
+ }
+}
+
+static void
+da1469x_uart_set_rx_pin_as_gpio(struct da1469x_uart *uart)
+{
+ int mode = uart->cfg->rx_pullup ? MCU_GPIO_MODE_INPUT_PULLUP : MCU_GPIO_MODE_INPUT;
+
+ if (uart->cfg->pin_rx >= 0) {
+ mcu_gpio_set_pin_function(uart->cfg->pin_rx, mode, MCU_GPIO_FUNC_GPIO);
+ }
+}
+
#if MYNEWT_VAL(UART_0) || MYNEWT_VAL(UART_1) || MYNEWT_VAL(UART_2)
static void
da1469x_uart_isr_thr_empty(struct da1469x_uart *uart)
@@ -194,6 +217,39 @@
}
static void
+da1469x_uart_reconnect_rx(void *arg)
+{
+ struct da1469x_uart *uart = (struct da1469x_uart *)arg;
+
+ /* RX pin high, reconfigure RX pin for UART */
+ if (hal_gpio_read(uart->cfg->pin_rx) == 1) {
+ hal_gpio_irq_release(uart->cfg->pin_rx);
+ uart->rx_disconnected = 0;
+ da1469x_uart_set_rx_pin(uart);
+ }
+}
+
+void
+da1469x_uart_busy(struct da1469x_uart *uart)
+{
+ UART2_Type *regs = uart->regs;
+ int8_t pin_rx = uart->cfg->pin_rx;
+ hal_gpio_pull_t mode = uart->cfg->rx_pullup ? HAL_GPIO_PULL_UP : HAL_GPIO_PULL_NONE;
+
+ (void)regs->UART2_USR_REG;
+ (void)regs->UART2_LSR_REG;
+ /* Busy due to low RX */
+ if (MYNEWT_VAL(MCU_UART_DICONNECT_RX_ON_BUSY) && hal_gpio_read(pin_rx) == 0) {
+ hal_gpio_irq_init(pin_rx, da1469x_uart_reconnect_rx, uart,
+ HAL_GPIO_TRIG_RISING, mode);
+ uart->rx_disconnected = 1;
+ hal_gpio_irq_enable(pin_rx);
+ return;
+ }
+ assert(0);
+}
+
+static void
da1469x_uart_common_isr(struct da1469x_uart *uart)
{
UART2_Type *regs;
@@ -221,9 +277,7 @@
case 0x06: /* receiver line status */
break;
case 0x07: /* busy detect */
- /* Clear the flag so if assert not defined no infinite loop here */
- (void)regs->UART2_USR_REG;
- assert(0);
+ da1469x_uart_busy(uart);
break;
case 0x0c: /* character timeout */
break;
@@ -421,9 +475,9 @@
uart->cfg = cfg;
mcu_gpio_set_pin_function(cfg->pin_tx, MCU_GPIO_MODE_OUTPUT, gpiofunc[0]);
- if (uart->cfg->pin_rx >= 0) {
- mcu_gpio_set_pin_function(cfg->pin_rx, MCU_GPIO_MODE_INPUT, gpiofunc[1]);
- }
+
+ da1469x_uart_set_rx_pin(uart);
+
if (cfg->pin_rts >= 0) {
mcu_gpio_set_pin_function(cfg->pin_rts, MCU_GPIO_MODE_OUTPUT, gpiofunc[2]);
}
@@ -446,7 +500,6 @@
UART2_Type *regs;
uint32_t reg;
uint32_t baudrate_cfg;
- uint32_t loop_count;
uart = da1469x_uart_resolve(port);
if (!uart) {
@@ -482,31 +535,12 @@
return SYS_ENOTSUP;
}
- /* Enable pullup if configured */
- if (uart->cfg->pin_rx >= 0 && uart->cfg->rx_pullup) {
- mcu_gpio_set_pin_function(uart->cfg->pin_rx, MCU_GPIO_MODE_INPUT_PULLUP,
- uart->rx_pin_func);
- }
-
- /*
- * If the UART is busy we are not allowed to write to the LCR register.
- * Doing so results in the "busy detect" error. Only reason UART should
- * be busy here is if something is driving RX low.
- *
- * XXX: the loop counter here is ugly for sure. Did not want to assume
- * an OS for the hal and instantiating a timer for this seemed pretty
- * heavyweight. There are 4 instructions and I realize this time will be
- * quite variable based on CPU clock and cache, etc.
- *
- * Did not want to simply poll and not break out as holding RX low would
- * cause an infinite loop here.
- */
- loop_count = 0;
- while (regs->UART2_USR_REG & UART2_UART2_USR_REG_UART_BUSY_Msk) {
- ++loop_count;
- if (loop_count > 10000) {
- return SYS_EBUSY;
- }
+ if (uart->cfg->pin_rx >= 0) {
+ /*
+ * Switch to GPIO during configuration to prevent landing up in
+ * busy state if RX line is low.
+ */
+ da1469x_uart_set_rx_pin_as_gpio(uart);
}
regs->UART2_LCR_REG |= UART2_UART2_LCR_REG_UART_DLAB_Msk;
@@ -558,10 +592,6 @@
NVIC_ClearPendingIRQ(uart->irqn);
NVIC_EnableIRQ(uart->irqn);
- if (uart->cfg->pin_rx >= 0) {
- da1469x_uart_rx_intr_enable(uart);
- }
-
/*
* We can acquire PD_COM here to be sure it's acquired only if everything is
* set properly. It's ok to setup UART without acquiring that domain earlier
@@ -571,6 +601,12 @@
*/
da1469x_pd_acquire(MCU_PD_DOMAIN_COM);
+ /* Reconnect RX pin to UART and enable RX interrupt. */
+ if (uart->cfg->pin_rx >= 0) {
+ da1469x_uart_rx_intr_enable(uart);
+ da1469x_uart_set_rx_pin(uart);
+ }
+
return 0;
}
@@ -578,6 +614,7 @@
hal_uart_close(int port)
{
struct da1469x_uart *uart;
+ int sr;
uart = da1469x_uart_resolve(port);
if (!uart) {
@@ -602,10 +639,18 @@
break;
}
- /* Set back to input with no pullup if pullup enabled */
- if (uart->cfg->pin_rx >= 0 && uart->cfg->rx_pullup) {
- mcu_gpio_set_pin_function(uart->cfg->pin_rx, MCU_GPIO_MODE_INPUT,
- uart->rx_pin_func);
+ /*
+ * If RX pin was changed to GPIO due busy state, change it back to UART RX
+ * releasing interrupt that was setup.
+ */
+ if (uart->cfg->pin_rx >= 0) {
+ OS_ENTER_CRITICAL(sr);
+ if (uart->rx_disconnected) {
+ hal_gpio_irq_release(uart->cfg->pin_rx);
+ uart->rx_disconnected = 0;
+ da1469x_uart_set_rx_pin(uart);
+ }
+ OS_EXIT_CRITICAL(sr);
}
da1469x_pd_release(MCU_PD_DOMAIN_COM);
diff --git a/hw/mcu/dialog/da1469x/syscfg.yml b/hw/mcu/dialog/da1469x/syscfg.yml
index 9369cf9..af65773 100644
--- a/hw/mcu/dialog/da1469x/syscfg.yml
+++ b/hw/mcu/dialog/da1469x/syscfg.yml
@@ -105,6 +105,13 @@
Used internally by the newt tool.
value: 1
+ MCU_UART_DICONNECT_RX_ON_BUSY:
+ description: >
+ If set to 1, UART RX pin will be configured to GPIO once busy state is
+ detected. UART block can stuck in busy state when RX line is set to 0.
+ This will result in continuous BUSY interrupt.
+ To prevent such case RX pin can be configured to GPIO.
+ value: 0
MCU_DMA_IRQ_PRIO:
description: >
Specifies the NVIC interrupt priority to assign for the DMA_IRQn
