ttwrplus: enable GPS

GPS was enabled using UART1 and Zephyr message queues.
UI is a bit crushed on the small 128x64 screen but hardware works as expected.

TG-553

platform/drivers/GPS/GPS_ttwrplus.c

@@ -0,0 +1,150 @@
+/***************************************************************************
+ *   Copyright (C) 2023 by Federico Amedeo Izzo IU2NUO,                    *
+ *                         Niccolò Izzo IU2KIN                             *
+ *                         Frederik Saraci IU2NRO                          *
+ *                         Silvano Seva IU2KWO                             *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 3 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
+ ***************************************************************************/
+
+#include <zephyr/drivers/uart.h>
+#include <zephyr/kernel.h>
+#include <interfaces/delays.h>
+#include <peripherals/gps.h>
+#include <hwconfig.h>
+#include <string.h>
+#include <pmu.h>
+
+
+#if DT_NODE_HAS_STATUS(DT_ALIAS(gps), okay)
+#define UART_GPS_DEV_NODE DT_ALIAS(gps)
+#else
+#error "Please select the correct gps UART device"
+#endif
+
+#define NMEA_MSG_SIZE 82
+
+K_MSGQ_DEFINE(gps_uart_msgq, NMEA_MSG_SIZE, 10, 4);
+
+static const struct device *const gps_dev = DEVICE_DT_GET(UART_GPS_DEV_NODE);
+
+// receive buffer used in UART ISR callback
+static char rx_buf[NMEA_MSG_SIZE];
+static uint16_t rx_buf_pos;
+
+
+static void gps_serialCb(const struct device *dev, void *user_data)
+{
+    uint8_t c;
+
+    if (uart_irq_update(gps_dev) == false)
+        return;
+
+    if (uart_irq_rx_ready(gps_dev) == false)
+        return;
+
+    // read until FIFO empty
+    while (uart_fifo_read(gps_dev, &c, 1) == 1)
+    {
+        if (c == '$' && rx_buf_pos > 0)
+        {
+            // terminate string
+            rx_buf[rx_buf_pos] = '\0';
+
+            // if queue is full, message is silently dropped
+            k_msgq_put(&gps_uart_msgq, &rx_buf, K_NO_WAIT);
+
+            // reset the buffer (it was copied to the msgq)
+            rx_buf_pos = 0;
+            rx_buf[rx_buf_pos++] = '$';
+        }
+        else if (rx_buf_pos < (sizeof(rx_buf) - 1))
+        {
+            rx_buf[rx_buf_pos++] = c;
+        }
+    }
+}
+
+
+void gps_init(const uint16_t baud)
+{
+    int ret = 0;
+
+    // Check if GPS UART is ready
+    if (device_is_ready(gps_dev) == false)
+    {
+        printk("UART device not found!\n");
+        return;
+    }
+
+    ret = uart_irq_callback_user_data_set(gps_dev, gps_serialCb, NULL);
+    if (ret < 0)
+    {
+        if (ret == -ENOTSUP)
+        {
+            printk("Interrupt-driven UART support not enabled\n");
+        }
+        else if (ret == -ENOSYS)
+        {
+            printk("UART device does not support interrupt-driven API\n");
+        }
+        else
+        {
+            printk("Error setting UART callback: %d\n", ret);
+        }
+
+        return;
+    }
+
+    uart_irq_rx_enable(gps_dev);
+}
+
+void gps_terminate()
+{
+    gps_disable();
+}
+
+void gps_enable()
+{
+    pmu_setGPSPower(true);
+}
+
+void gps_disable()
+{
+    pmu_setGPSPower(false);
+}
+
+bool gps_detect(uint16_t timeout)
+{
+    return true;
+}
+
+int gps_getNmeaSentence(char *buf, const size_t maxLength)
+{
+    k_msgq_get(&gps_uart_msgq, buf, K_FOREVER);
+    return 0;
+}
+
+bool gps_nmeaSentenceReady()
+{
+    return k_msgq_num_used_get(&gps_uart_msgq) != 0;
+}
+
+void gps_waitForNmeaSentence()
+{
+    while (k_msgq_num_used_get(&gps_uart_msgq) != 0)
+    {
+        sleepFor(0, 100);
+    }
+}

platform/targets/ttwrplus/CMakeLists.txt

@@ -16,6 +16,7 @@ target_sources(app
     ${OPENRTX_ROOT}/platform/drivers/keyboard/keyboard_ttwrplus.c
     ${OPENRTX_ROOT}/platform/drivers/baseband/radio_ttwrplus.cpp
     ${OPENRTX_ROOT}/platform/drivers/baseband/AT1846S_SA8x8.cpp
+    ${OPENRTX_ROOT}/platform/drivers/GPS/GPS_ttwrplus.c
 
     ${OPENRTX_ROOT}/platform/drivers/stubs/audio_stub.c
     ${OPENRTX_ROOT}/platform/drivers/stubs/cps_io_stub.c

platform/targets/ttwrplus/hwconfig.h

@@ -29,6 +29,7 @@
 #define SCREEN_WIDTH  DT_PROP(DISPLAY, width)
 #define SCREEN_HEIGHT DT_PROP(DISPLAY, height)
 #define PIX_FMT_BW
+#define GPS_PRESENT
 
 #define BAT_LIPO_1S
 

platform/targets/ttwrplus/pmu.cpp

@@ -146,7 +146,7 @@ void pmu_init()
     PMU.enableALDO2();
 
     //! ALDO4 GNSS VDD
-    PMU.enableALDO4();
+    PMU.disableALDO4();
 
     //! BLDO1 MIC VDD
     PMU.enableBLDO1();
@@ -305,3 +305,11 @@ void pmu_setBasebandPower(bool enable)
     else
         PMU.disableDC3();
 }
+
+void pmu_setGPSPower(bool enable)
+{
+    if (enable)
+        PMU.enableALDO4();
+    else
+        PMU.disableALDO4();
+}

platform/targets/ttwrplus/pmu.h

@@ -27,6 +27,7 @@ extern "C" {
 void pmu_init();
 uint16_t pmu_getVbat();
 void pmu_setBasebandPower(bool enable);
+void pmu_setGPSPower(bool enable);
 
 #ifdef __cplusplus
 }

platform/targets/ttwrplus/ttwrplus.dts

@@ -18,6 +18,7 @@
         i2c-0 = &i2c0;
         watchdog0 = &wdt0;
         radio = &uart0;
+        gps = &uart1;
         radio-pwr = &radio_pwr;
         radio-pdn = &radio_pdn;
         radio-ptt = &radio_ptt;
@@ -94,6 +95,13 @@
     pinctrl-names = "default";
 };
 
+&uart1 {
+    status = "okay";
+    current-speed = <9600>;
+    pinctrl-0 = <&uart1_default>;
+    pinctrl-names = "default";
+};
+
 &i2c0 {
     status = "okay";
     clock-frequency = <I2C_BITRATE_FAST>;
@@ -201,6 +209,17 @@
         };
     };
 
+    uart1_default: uart1_default {
+        group1 {
+            pinmux = <UART1_TX_GPIO6>;
+            output-high;
+        };
+        group2 {
+            pinmux = <UART1_RX_GPIO5>;
+            bias-pull-up;
+        };
+    };
+
     i2c0_default: i2c0_default {
         group1 {
             pinmux = <I2C0_SDA_GPIO8>,