icE1usb fw: Import GPS module driver code
This only initializes the GPS module and keeps track of the
antenna and fix status
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: I24811f872fafefc7f8dfaa3028c4288001a87d2f
diff --git a/firmware/ice40-riscv/icE1usb/Makefile b/firmware/ice40-riscv/icE1usb/Makefile
index 36fd921..6725f6a 100644
--- a/firmware/ice40-riscv/icE1usb/Makefile
+++ b/firmware/ice40-riscv/icE1usb/Makefile
@@ -48,6 +48,7 @@
HEADERS_app=\
config.h \
e1.h \
+ gps.h \
ice1usb_proto.h \
misc.h \
usb_desc_ids.h \
@@ -59,6 +60,7 @@
SOURCES_app=\
e1.c \
fw_app.c \
+ gps.c \
misc.c \
usb_desc_app.c \
usb_dev.c \
diff --git a/firmware/ice40-riscv/icE1usb/fw_app.c b/firmware/ice40-riscv/icE1usb/fw_app.c
index 880d2d6..c5c2b7c 100644
--- a/firmware/ice40-riscv/icE1usb/fw_app.c
+++ b/firmware/ice40-riscv/icE1usb/fw_app.c
@@ -14,6 +14,7 @@
#include "console.h"
#include "e1.h"
+#include "gps.h"
#include "led.h"
#include "misc.h"
#include "mini-printf.h"
@@ -96,6 +97,9 @@
pdm_set(PDM_CLK_HI, true, 2048, false);
pdm_set(PDM_CLK_LO, false, 0, false);
+ /* GPS init */
+ gps_init();
+
/* Enable USB directly */
usb_init(&app_stack_desc);
usb_dev_init();
@@ -161,5 +165,8 @@
/* E1 poll */
usb_e1_poll();
+
+ /* GPS poll */
+ gps_poll();
}
}
diff --git a/firmware/ice40-riscv/icE1usb/gps.c b/firmware/ice40-riscv/icE1usb/gps.c
new file mode 100644
index 0000000..2fd6ab8
--- /dev/null
+++ b/firmware/ice40-riscv/icE1usb/gps.c
@@ -0,0 +1,286 @@
+/*
+ * gps.c
+ *
+ * Copyright (C) 2019-2022 Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "console.h"
+#include "gps.h"
+#include "misc.h"
+#include "utils.h"
+
+#include "config.h"
+
+
+struct gps_uart {
+ uint32_t data;
+ uint32_t csr;
+} __attribute__((packed,aligned(4)));
+
+#define GPS_UART_CSR_DIV(baud) ((SYS_CLK_FREQ+(baud)/2)/(baud)-2)
+#define GPS_UART_CSR_TX_EMPTY (1 << 29)
+#define GPS_UART_DATA_EMPTY (1 << 31)
+
+static volatile struct gps_uart * const gps_uart_regs = (void*)(GPS_UART_BASE);
+
+
+static struct {
+ /* NMEA rx state */
+ struct {
+ enum {
+ GNS_WAIT = 0,
+ GNS_READ = 1,
+ GNS_CK_HI = 2,
+ GNS_CK_LO = 3,
+ GNS_END_CR = 4,
+ GNS_END_LF = 5,
+ } state;
+
+ int len;
+ uint8_t cksum;
+ char buf[95]; /* Max length is actually 82 + 1 (\0) */
+ } nmea;
+
+ /* Current lock state */
+ struct {
+ bool valid;
+ } fix;
+
+ /* Reported antenna state */
+ enum gps_antenna_state antenna;
+} g_gps;
+
+
+static void
+_gps_empty(bool wait_eol)
+{
+ bool eol = false;
+
+ uint32_t c;
+ while (1) {
+ c = gps_uart_regs->data;
+ if (c & GPS_UART_DATA_EMPTY) {
+ if (!wait_eol || eol)
+ break;
+ } else {
+ eol = (c == '\n');
+ }
+ }
+}
+
+static void
+_gps_send(const char *s)
+{
+ char cksum = 0;
+
+ /* Start sentence */
+ gps_uart_regs->data = '$';
+
+ /* Send payload */
+ while (*s)
+ cksum ^= (gps_uart_regs->data = *s++);
+
+ /* Send checksum */
+ gps_uart_regs->data = '*';
+
+ s = hexstr(&cksum, 1, false);
+ gps_uart_regs->data = *s++;
+ gps_uart_regs->data = *s++;
+
+ gps_uart_regs->data = '\r';
+ gps_uart_regs->data = '\n';
+}
+
+static const char *
+_gps_query(void)
+{
+ uint32_t c;
+ while (1) {
+ /* Get next char */
+ c = gps_uart_regs->data;
+ if (c & GPS_UART_DATA_EMPTY)
+ break;
+
+ /* Always store it */
+ if (g_gps.nmea.len == sizeof(g_gps.nmea.buf))
+ g_gps.nmea.state = GNS_WAIT;
+ else
+ g_gps.nmea.buf[g_gps.nmea.len++] = c;
+
+ /* State */
+ if (c == '$') {
+ /* '$' always triggers reset */
+ g_gps.nmea.state = GNS_READ;
+ g_gps.nmea.cksum = 0;
+ g_gps.nmea.len = 1;
+ g_gps.nmea.buf[0] = '$';
+ } else {
+ switch (g_gps.nmea.state) {
+ case GNS_READ:
+ if (c == '*')
+ g_gps.nmea.state = GNS_CK_HI;
+ else
+ g_gps.nmea.cksum ^= c;
+ break;
+ case GNS_CK_HI:
+ g_gps.nmea.cksum ^= hexval(c) << 4;
+ g_gps.nmea.state = GNS_CK_LO;
+ break;
+ case GNS_CK_LO:
+ g_gps.nmea.cksum ^= hexval(c);
+ g_gps.nmea.state = GNS_END_CR;
+ break;
+ case GNS_END_CR:
+ g_gps.nmea.state = (c == '\r') ? GNS_END_LF : GNS_WAIT;
+ break;
+ case GNS_END_LF:
+ g_gps.nmea.state = GNS_WAIT;
+ g_gps.nmea.buf[g_gps.nmea.len] = 0x00;
+ if (c == '\n')
+ return g_gps.nmea.buf;
+ break;
+ default:
+ g_gps.nmea.state = GNS_WAIT;
+ g_gps.nmea.len = 0;
+ break;
+ }
+ }
+ }
+ return NULL;
+}
+
+void
+_gps_parse_nmea(const char *nmea)
+{
+ /* Very basic parsing, we just look at GSA messages and consider
+ * that if we have a 3D fix with PDOP < 5, the timing data should
+ * be usable
+ */
+ if (!strncmp(nmea, "$GPGSA", 6))
+ {
+ /* Check for Autonomous 3D fix (fixed field positions) */
+ if ((nmea[7] != 'A') || (nmea[9] != '3')) {
+ g_gps.fix.valid = false;
+ return;
+ }
+
+ /* Find PDOP */
+ const char *p = nmea;
+ for (int i=0; (i < 15) && (*p != '*'); i += (*(p++)==',') );
+
+ /* Is it low enough ? */
+ g_gps.fix.valid = (p[1] < '5');
+ }
+
+ /* Parse TXT ANTENNA Status */
+ if (!strncmp(nmea, "$GPTXT", 6) && nmea[13] == '0' && nmea[14] == '1')
+ {
+ if (!strncmp(&nmea[16], "ANTENNA OK", 10))
+ g_gps.antenna = ANT_OK;
+ else if (!strncmp(&nmea[16], "ANTENNA OPEN", 12))
+ g_gps.antenna = ANT_OPEN;
+ else if (!strncmp(&nmea[16], "ANTENNA SHORT", 13))
+ g_gps.antenna = ANT_SHORT;
+ else
+ g_gps.antenna = ANT_UNKNOWN;
+ }
+}
+
+
+bool
+gps_has_valid_fix(void)
+{
+ return g_gps.fix.valid;
+}
+
+enum gps_antenna_state
+gps_antenna_status(void)
+{
+ return g_gps.antenna;
+}
+
+void
+gps_poll(void)
+{
+ const char *nmea;
+
+ /* Check if we have anything from the module */
+ nmea = _gps_query();
+ if (!nmea)
+ return;
+
+ /* If we do, process it locally to update our state */
+ _gps_parse_nmea(nmea);
+}
+
+void
+gps_init(void)
+{
+ int i;
+
+ /* State init */
+ memset(&g_gps, 0x00, sizeof(g_gps));
+
+ /* Configure reset gpio */
+ gpio_out(3, false);
+ gpio_dir(3, true);
+
+ /* Attempt reset sequence at 9600 baud and then 115200 baud */
+ for (i=0; i<2; i++)
+ {
+ uint32_t start_time = time_now_read();
+ bool init_ok;
+
+ /* Assert reset */
+ gpio_out(3, false);
+
+ /* Configure uart and empty buffer */
+ gps_uart_regs->csr = i ? GPS_UART_CSR_DIV(115200) : GPS_UART_CSR_DIV(9600);
+ _gps_empty(false);
+
+ /* Wait 100 ms */
+ delay(100);
+
+ /* Release reset line */
+ gpio_out(3, true);
+
+ /* Wait for first line of output as sign it's ready, timeout after 1s */
+ while (!time_elapsed(start_time, SYS_CLK_FREQ))
+ if ((init_ok = (_gps_query() != NULL)))
+ break;
+
+ if (init_ok) {
+ printf("[+] GPS ok at %d baud\n", i ? 115200 : 9600);
+ break;
+ }
+ }
+
+ /* Failed ? */
+ if (i == 2) {
+ printf("[!] GPS init failed\n");
+ return;
+ }
+
+ /* If success was at 9600 baud, need to speed up */
+ if (i == 0) {
+ /* Configure GPS to use serial at 115200 baud */
+ _gps_send("PCAS01,5");
+
+ /* Add dummy byte which will be mangled during baudrate switch ... */
+ gps_uart_regs->data = 0x00;
+ while (!(gps_uart_regs->csr & GPS_UART_CSR_TX_EMPTY));
+
+ /* Set uart to 115200 and empty uart buffer, line aligned */
+ gps_uart_regs->csr = GPS_UART_CSR_DIV(115200) ;
+ _gps_empty(true);
+ }
+
+ /* Configure GPS to be GPS-only (no GLONASS/BEIDOU) */
+ _gps_send("PCAS04,1");
+}
diff --git a/firmware/ice40-riscv/icE1usb/gps.h b/firmware/ice40-riscv/icE1usb/gps.h
new file mode 100644
index 0000000..57ef271
--- /dev/null
+++ b/firmware/ice40-riscv/icE1usb/gps.h
@@ -0,0 +1,23 @@
+/*
+ * gps.h
+ *
+ * Copyright (C) 2019-2022 Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <stdbool.h>
+
+enum gps_antenna_state {
+ ANT_UNKNOWN = 0,
+ ANT_OK,
+ ANT_OPEN,
+ ANT_SHORT
+};
+
+bool gps_has_valid_fix(void);
+enum gps_antenna_state gps_antenna_status(void);
+
+void gps_poll(void);
+void gps_init(void);