CS7000: added GPS support

meson.build

@@ -474,6 +474,7 @@ cs7000_src = ['platform/drivers/NVM/nvmem_CS7000.c',
              'platform/drivers/GPIO/gpio_shiftReg.c',
              'platform/drivers/SPI/spi_custom.c',
              'platform/drivers/SPI/spi_bitbang.c',
+             'platform/drivers/GPS/GPS_CS7000.cpp',
              'platform/targets/CS7000/hwconfig.c',
              'platform/targets/CS7000/platform.c']
 

platform/drivers/GPS/GPS_CS7000.cpp

@@ -0,0 +1,175 @@
+/***************************************************************************
+ *   Copyright (C) 2024 by 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 <kernel/scheduler/scheduler.h>
+#include <interfaces/delays.h>
+#include <peripherals/gpio.h>
+#include <peripherals/gps.h>
+#include <hwconfig.h>
+#include <string.h>
+#include <miosix.h>
+#include <rcc.h>
+
+static size_t bufPos = 0;
+static size_t maxPos = 0;
+static char   *dataBuf;
+static bool   receiving = false;
+
+using namespace miosix;
+static Thread *gpsWaiting = 0;
+
+void __attribute__((used)) GpsUsartImpl()
+{
+    if(USART6->SR & USART_SR_RXNE)
+    {
+        char value = USART6->DR;
+
+        if((receiving == false) && (value == '$') && (bufPos == 0))
+        {
+            receiving = true;
+        }
+
+        if(receiving)
+        {
+            if(bufPos == maxPos)
+            {
+                receiving = false;
+            }
+
+            char prevChar   = dataBuf[bufPos - 1];
+            dataBuf[bufPos] = value;
+            bufPos += 1;
+
+            if((prevChar == '\r') && (value == '\n'))
+            {
+                receiving = false;
+                bufPos -= 1;
+            }
+        }
+
+        if((receiving == false) && (bufPos != 0))
+        {
+            // NMEA sentence received, turn off serial port
+            USART6->CR1 &= ~USART_CR1_UE;
+
+            if(gpsWaiting)
+            {
+                gpsWaiting->IRQwakeup();
+                if(gpsWaiting->IRQgetPriority()>
+                    Thread::IRQgetCurrentThread()->IRQgetPriority())
+                        Scheduler::IRQfindNextThread();
+                gpsWaiting = 0;
+            }
+        }
+    }
+
+    USART6->SR = 0;
+}
+
+void __attribute__((naked)) USART6_IRQHandler()
+{
+    saveContext();
+    asm volatile("bl _Z12GpsUsartImplv");
+    restoreContext();
+}
+
+
+void gps_init(const uint16_t baud)
+{
+    gpio_setMode(GPS_RXD, ALTERNATE | ALTERNATE_FUNC(8));
+
+    RCC->APB2ENR |= RCC_APB2ENR_USART6EN;
+    __DSB();
+
+    uint32_t quot = rcc_getBusClock(PERIPH_BUS_APB2);
+    quot = (2 * quot) / baud;
+
+    USART6->BRR  = (quot / 2) + (quot & 1);
+    USART6->CR3 |= USART_CR3_ONEBIT;
+    USART6->CR1  = USART_CR1_RE
+                 | USART_CR1_RXNEIE;
+
+    NVIC_SetPriority(USART6_IRQn, 14);
+}
+
+void gps_terminate()
+{
+    gps_disable();
+
+    RCC->APB2ENR &= ~RCC_APB2ENR_USART6EN;
+}
+
+void gps_enable()
+{
+    // Enable IRQ
+    NVIC_ClearPendingIRQ(USART6_IRQn);
+    NVIC_EnableIRQ(USART6_IRQn);
+}
+
+void gps_disable()
+{
+    USART6->CR1 &= ~USART_CR1_UE;
+    NVIC_DisableIRQ(USART6_IRQn);
+
+    receiving = false;
+    bufPos    = 0;
+}
+
+bool gps_detect(uint16_t timeout)
+{
+    (void) timeout;
+
+    return true;
+}
+
+int gps_getNmeaSentence(char *buf, const size_t maxLength)
+{
+    memset(buf, 0x00, maxLength);
+    bufPos  = 0;
+    maxPos  = maxLength;
+    dataBuf = buf;
+
+    // Enable serial port
+    USART6->CR1 |= USART_CR1_UE;
+
+    return 0;
+}
+
+bool gps_nmeaSentenceReady()
+{
+    return (receiving == false) && (bufPos > 0);
+}
+
+void gps_waitForNmeaSentence()
+{
+    /*
+     * Put the calling thread in waiting status until a complete sentence is ready.
+     */
+    {
+        FastInterruptDisableLock dLock;
+        gpsWaiting = Thread::IRQgetCurrentThread();
+        do
+        {
+            Thread::IRQwait();
+            {
+                FastInterruptEnableLock eLock(dLock);
+                Thread::yield();
+            }
+        }
+        while(gpsWaiting);
+    }
+}

platform/targets/CS7000/hwconfig.h

@@ -66,6 +66,9 @@ extern const struct sky73210 pll;
 /* Device supports M17 mode */
 #define CONFIG_M17
 
+/* Device has a GPS chip */
+#define CONFIG_GPS
+
 #ifdef __cplusplus
 }
 #endif

platform/targets/CS7000/pinmap.h

@@ -148,8 +148,8 @@
 #define PHONE_DETECT  GPIOA,13
 
 /* GPS */
-#define GPS_RXD       GPIOC,6
-#define GPS_TXD       GPIOC,7
+#define GPS_TXD       GPIOC,6
+#define GPS_RXD       GPIOC,7
 
 /* Accessory connector */
 #define PHONE_TXD     GPIOA,0