Cpld autodetect & boot splash screen (#1888)

* added delayed error message when hackrf cpld initialization fails

* refactoring

* implemented portapack cpld autodetection

* refactoring

* fixed valid config range

* added lcd fast setup

* added boot splash screen

* added one frame delay to remove flickering

* fixed config persistence

firmware/application/main.cpp

@@ -162,6 +162,8 @@ static void event_loop() {
 }
 
 int main(void) {
+    first_if.init(); /* To avoid initial short Ant_DC_Bias pulse ,we need quick set up GP01_RFF507X =1 */
+
     if (config_mode_should_enter()) {
         config_mode_clear();
         config_mode_run();
@@ -169,15 +171,13 @@ int main(void) {
 
     config_mode_set();
 
-    first_if.init(); /* To avoid initial short Ant_DC_Bias pulse ,we need quick set up GP01_RFF507X =1 */
-
     switch (portapack::init()) {
         case portapack::init_status_t::INIT_HACKRF_CPLD_FAILED:
             portapack::init_error = "HACKRF CPLD FAILED";
             [[fallthrough]];
 
         case portapack::init_status_t::INIT_SUCCESS:
-            portapack::display.init();
+
             config_mode_clear();
 
             lcd_frame_sync_configure();

firmware/application/portapack.cpp

@@ -28,6 +28,7 @@
 #include "hackrf_hal.hpp"
 #include "hackrf_gpio.hpp"
 using namespace hackrf::one;
+#include "jtag_target_gpio.hpp"
 
 #include "clock_manager.hpp"
 #include "event_m0.hpp"
@@ -50,6 +51,7 @@ using asahi_kasei::ak4951::AK4951;
 #include "file.hpp"
 #include "sd_card.hpp"
 #include "string_format.hpp"
+#include "bitmap.hpp"
 
 namespace portapack {
 
@@ -174,51 +176,22 @@ constexpr I2CConfig i2c_config_fast_clock{
 enum class PortaPackModel {
     R1_20150901,
     R2_20170522,
+    AGM,
+    AUTODETECT,
 };
 
 static bool save_config(int8_t value) {
     persistent_memory::set_config_cpld(value);
-    if (sd_card::status() == sd_card::Status::Mounted) {
+    portapack::persistent_memory::cache::persist();
-        ensure_directory("/hardware");
-        File file;
-        auto sucess = file.create("/hardware/settings.txt");
-        if (!sucess.is_valid()) {
-            file.write_line(to_string_dec_uint(value));
-        }
-    }
     return true;
 }
 
-int read_file(std::string name) {
-    std::string return_string = "";
-    File file;
-    auto success = file.open(name);
-
-    if (!success.is_valid()) {
-        char one_char[1];
-        for (size_t pointer = 0; pointer < file.size(); pointer++) {
-            file.seek(pointer);
-            file.read(one_char, 1);
-            return_string += one_char[0];
-        }
-        return std::stoi(return_string);
-    }
-    return -1;
-}
-
 static int load_config() {
     static Optional<int> config_value;
     if (!config_value.is_valid()) {
         int8_t value = portapack::persistent_memory::config_cpld();
-        if ((value <= 0 || value >= 5) && sd_card::status() == sd_card::Status::Mounted) {
-            int data = read_file("/hardware/settings.txt");
-            if (data != -1) {
-                config_value = data;
-            }
-        } else {
         config_value = value;
     }
-    }
     return config_value.value();
 }
 
@@ -226,25 +199,38 @@ static PortaPackModel portapack_model() {
     static Optional<PortaPackModel> model;
 
     if (!model.is_valid()) {
-        const auto switches_state = get_switches_state();
+        jtag::GPIOTarget target{
+            portapack::gpio_cpld_tck,
+            portapack::gpio_cpld_tms,
+            portapack::gpio_cpld_tdi,
+            portapack::gpio_cpld_tdo};
+        jtag::JTAG jtag{target};
+        portapack::cpld::CPLD cpld{jtag};
+
+        cpld.reset();
+        cpld.run_test_idle();
+        uint32_t idcode = cpld.get_idcode();
+        if (idcode == 0x25610) {
+            model = PortaPackModel::AGM;
+        } else {
+            const auto switches_state = swizzled_switches();
+            // chDbgPanic(to_string_hex((uint32_t)switches_state.count(), 8).c_str());
             //  Only save config if no other multi key boot action is triggered (like pmem reset)
-        if (switches_state.count() == 1) {
+            if (((switches_state >> (size_t)ui::KeyEvent::Up) & 1) == 1) {
-            if (switches_state[(size_t)ui::KeyEvent::Up]) {
                 save_config(1);
                 // model = PortaPackModel::R2_20170522; // Commented these out as they should be set down below anyway
-            } else if (switches_state[(size_t)ui::KeyEvent::Down]) {
+            } else if (((switches_state >> (size_t)ui::KeyEvent::Down) & 1) == 1) {
                 save_config(2);
                 // model = PortaPackModel::R1_20150901;
-            } else if (switches_state[(size_t)ui::KeyEvent::Left]) {
+            } else if (((switches_state >> (size_t)ui::KeyEvent::Left) & 1) == 1) {
                 save_config(3);
                 // model = PortaPackModel::R1_20150901;
-            } else if (switches_state[(size_t)ui::KeyEvent::Right]) {
+            } else if (((switches_state >> (size_t)ui::KeyEvent::Right) & 1) == 1) {
                 save_config(4);
                 // model = PortaPackModel::R2_20170522;
-            } else if (switches_state[(size_t)ui::KeyEvent::Select]) {
+            } else if (((switches_state >> (size_t)ui::KeyEvent::Select) & 1) == 1) {
                 save_config(0);
             }
-        }
 
             if (load_config() == 1) {
                 model = PortaPackModel::R2_20170522;
@@ -255,10 +241,7 @@ static PortaPackModel portapack_model() {
             } else if (load_config() == 4) {
                 model = PortaPackModel::R2_20170522;
             } else {
-            if (audio_codec_wm8731.detected()) {
+                model = PortaPackModel::AUTODETECT;
-                model = PortaPackModel::R1_20150901;  // H1R1
-            } else {
-                model = PortaPackModel::R2_20170522;  // H1R2, H2, H2+
             }
         }
     }
@@ -345,6 +328,129 @@ static void shutdown_base() {
     clock_manager.shutdown();
 }
 
+static void set_cpu_clock_speed() {
+    /* Incantation from LPC43xx UM10503 section 12.2.1.1, to bring the M4
+     * core clock speed to the 110 - 204MHz range.
+     */
+
+    /* Step into the 90-110MHz M4 clock range */
+    /* OG:
+     * 	Fclkin = 40M
+     * 		/N=2 = 20M = PFDin
+     * 	Fcco = PFDin * (M=10) = 200M
+     * r9:
+     * 	Fclkin = 10M
+     * 		/N=1 = 10M = PFDin
+     * 	Fcco = PFDin * (M=20) = 200M
+     * Fclk = Fcco / (2*(P=1)) = 100M
+     */
+    cgu::pll1::ctrl({
+        .pd = 1,
+        .bypass = 0,
+        .fbsel = 0,
+        .direct = 0,
+        .psel = 0,
+        .autoblock = 1,
+        .nsel = hackrf_r9 ? 0UL : 1UL,
+        .msel = hackrf_r9 ? 19UL : 9UL,
+        .clk_sel = cgu::CLK_SEL::GP_CLKIN,
+    });
+
+    cgu::pll1::enable();
+    while (!cgu::pll1::is_locked())
+        ;
+
+    set_clock_config(clock_config_pll1_step);
+
+    /* Delay >50us at 90-110MHz clock speed */
+    volatile uint32_t delay = 1400;
+    while (delay--)
+        ;
+
+    set_clock_config(clock_config_pll1);
+
+    /* Remove /2P divider from PLL1 output to achieve full speed */
+    cgu::pll1::direct();
+}
+
+static void draw_splash_screen_icon(int16_t n, const ui::Bitmap& bitmap) {
+    ui::Painter painter;
+
+    painter.draw_bitmap(
+        {portapack::display.width() / 2 - 8 - 40 + (n * 20), portapack::display.height() / 2 - 8 + 40},
+        bitmap,
+        ui::Color::white(),
+        ui::Color::black());
+}
+
+static bool is_portapack_present() {
+    systime_t timeout = 50;
+    uint8_t wm8731_reset_command[] = {0x0f, 0x00};
+    if (i2c0.transmit(0x1a /* wm8731 */, wm8731_reset_command, 2, timeout) == false) {
+        audio_codec_ak4951.reset();
+        uint8_t ak4951_init_command[] = {0x00, 0x00};
+        i2c0.transmit(0x12 /* ak4951 */, ak4951_init_command, 2, timeout);
+        chThdSleepMilliseconds(10);
+        if (i2c0.transmit(0x12 /* ak4951 */, ak4951_init_command, 2, timeout) == false) {
+            shutdown_base();
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static bool check_portapack_cpld() {
+    switch (portapack_model()) {
+        case PortaPackModel::AUTODETECT: {
+            portapack::cpld::CpldUpdateStatus result = portapack::cpld::update_autodetect(
+                portapack::cpld::rev_20150901::config, portapack::cpld::rev_20170522::config);
+            if (result != portapack::cpld::CpldUpdateStatus::Success) {
+                shutdown_base();
+                return false;
+            }
+        } break;
+
+        case PortaPackModel::R1_20150901:
+        case PortaPackModel::R2_20170522: {
+            portapack::cpld::CpldUpdateStatus result = portapack::cpld::update_if_necessary(portapack_cpld_config());
+            if (result == portapack::cpld::CpldUpdateStatus::Program_failed) {
+                chThdSleepMilliseconds(10);
+                // Mode left (R1) and right (R2,H2,H2+) bypass going into hackrf mode after failing CPLD update
+                // Mode center (autodetect), up (R1) and down (R2,H2,H2+) will go into hackrf mode after failing CPLD update
+                if (load_config() != 3 /* left */ && load_config() != 4 /* right */) {
+                    shutdown_base();
+                    return false;
+                }
+            }
+        } break;
+
+        case PortaPackModel::AGM:
+            // the AGM devices are always factory flashed. so do nothing
+            break;
+    }
+
+    return true;
+}
+
+static void initialize_boot_splash_screen() {
+    ui::Painter painter;
+    portapack::display.init();
+
+    painter.fill_rectangle(
+        {0, 0, portapack::display.width(), portapack::display.height()},
+        ui::Color::black());
+
+    chThdSleepMilliseconds(17);
+    portapack::backlight()->on();
+
+    painter.draw_bitmap(
+        {portapack::display.width() / 2 - 40, portapack::display.height() / 2 - 8},
+        ui::bitmap_titlebar_image,
+        ui::Color::white(),
+        ui::Color::black());
+}
+
 /* Clock scheme after exiting bootloader in SPIFI mode:
  *
  * XTAL_OSC = powered down
@@ -396,23 +502,24 @@ init_status_t init() {
 
     i2c0.start(i2c_config_boot_clock);
 
-    // Keeping this here for now incase we need to revert
-    // if( !portapack::cpld::update_if_necessary(portapack_cpld_config()) ) {
-    // 	shutdown_base();
-    // 	return false;
-    // }
-
-    // if( !hackrf::cpld::load_sram() ) {
-    // 	chSysHalt();
-    // }
     chThdSleepMilliseconds(100);
 
     configure_pins_portapack();
 
     portapack::io.init();
+    persistent_memory::cache::init();
+
+    const auto switches_state = swizzled_switches() & (~(0xC0 | 0x80));
+    bool lcd_fast_setup = switches_state == 0 && portapack::display.read_display_status();
+
+    if (lcd_fast_setup) {
+        initialize_boot_splash_screen();
+    } else {
+        if (check_portapack_cpld() == false)
+            return init_status_t::INIT_PORTAPACK_CPLD_FAILED;
+    }
 
     /* Cache some configuration data from persistent memory. */
-    persistent_memory::cache::init();
     rtc_time::dst_init();
     chThdSleepMilliseconds(10);
 
@@ -425,48 +532,10 @@ init_status_t init() {
     set_clock_config(clock_config_irc);
     cgu::pll1::disable();
 
-    /* Incantation from LPC43xx UM10503 section 12.2.1.1, to bring the M4
+    set_cpu_clock_speed();
-     * core clock speed to the 110 - 204MHz range.
-     */
 
-    /* Step into the 90-110MHz M4 clock range */
+    if (lcd_fast_setup)
-    /* OG:
+        draw_splash_screen_icon(0, ui::bitmap_icon_memory);
-     * 	Fclkin = 40M
-     * 		/N=2 = 20M = PFDin
-     * 	Fcco = PFDin * (M=10) = 200M
-     * r9:
-     * 	Fclkin = 10M
-     * 		/N=1 = 10M = PFDin
-     * 	Fcco = PFDin * (M=20) = 200M
-     * Fclk = Fcco / (2*(P=1)) = 100M
-     */
-    cgu::pll1::ctrl({
-        .pd = 1,
-        .bypass = 0,
-        .fbsel = 0,
-        .direct = 0,
-        .psel = 0,
-        .autoblock = 1,
-        .nsel = hackrf_r9 ? 0UL : 1UL,
-        .msel = hackrf_r9 ? 19UL : 9UL,
-        .clk_sel = cgu::CLK_SEL::GP_CLKIN,
-    });
-
-    cgu::pll1::enable();
-    while (!cgu::pll1::is_locked())
-        ;
-
-    set_clock_config(clock_config_pll1_step);
-
-    /* Delay >50us at 90-110MHz clock speed */
-    volatile uint32_t delay = 1400;
-    while (delay--)
-        ;
-
-    set_clock_config(clock_config_pll1);
-
-    /* Remove /2P divider from PLL1 output to achieve full speed */
-    cgu::pll1::direct();
 
     usb_serial.initialize();
 
@@ -474,18 +543,11 @@ init_status_t init() {
     chThdSleepMilliseconds(10);
 
     /* Check if portapack is attached by checking if any of the two audio chips is present. */
-    systime_t timeout = 50;
+    if (lcd_fast_setup == false && is_portapack_present() == false)
-    uint8_t wm8731_reset_command[] = {0x0f, 0x00};
-    if (i2c0.transmit(0x1a /* wm8731 */, wm8731_reset_command, 2, timeout) == false) {
-        audio_codec_ak4951.reset();
-        uint8_t ak4951_init_command[] = {0x00, 0x00};
-        i2c0.transmit(0x12 /* ak4951 */, ak4951_init_command, 2, timeout);
-        chThdSleepMilliseconds(10);
-        if (i2c0.transmit(0x12 /* ak4951 */, ak4951_init_command, 2, timeout) == false) {
-            shutdown_base();
         return init_status_t::INIT_NO_PORTAPACK;
-        }
+
-    }
+    if (lcd_fast_setup)
+        draw_splash_screen_icon(1, ui::bitmap_icon_remote);
 
     touch::adc::init();
     controls_init();
@@ -501,23 +563,20 @@ init_status_t init() {
 
     chThdSleepMilliseconds(10);
 
-    portapack::cpld::CpldUpdateStatus result = portapack::cpld::update_if_necessary(portapack_cpld_config());
+    if (lcd_fast_setup)
-    if (result == portapack::cpld::CpldUpdateStatus::Program_failed) {
+        draw_splash_screen_icon(2, ui::bitmap_icon_sd);
-        chThdSleepMilliseconds(10);
-        // Mode left (R1) and right (R2,H2,H2+) bypass going into hackrf mode after failing CPLD update
-        // Mode center (autodetect), up (R1) and down (R2,H2,H2+) will go into hackrf mode after failing CPLD update
-        if (load_config() != 3 /* left */ && load_config() != 4 /* right */) {
-            shutdown_base();
-            return init_status_t::INIT_PORTAPACK_CPLD_FAILED;
-        }
-    }
 
     init_status_t return_code = init_status_t::INIT_SUCCESS;
-
     if (!hackrf::cpld::load_sram()) {
+        if (lcd_fast_setup)
+            chDbgPanic("HACKRF CPLD FAILED");
+
         return_code = init_status_t::INIT_HACKRF_CPLD_FAILED;
     }
 
+    if (lcd_fast_setup)
+        draw_splash_screen_icon(3, ui::bitmap_icon_hackrf);
+
     chThdSleepMilliseconds(10);  // This delay seems to solve white noise audio issues
 
     LPC_CREG->DMAMUX = portapack::gpdma_mux;
@@ -527,6 +586,13 @@ init_status_t init() {
 
     audio::init(portapack_audio_codec());
 
+    if (lcd_fast_setup)
+        draw_splash_screen_icon(4, ui::bitmap_icon_speaker);
+    else {
+        portapack::display.init();
+        portapack::backlight()->on();
+    }
+
     return return_code;
 }
 

firmware/common/cpld_update.cpp

@@ -23,6 +23,7 @@
 
 #include "hackrf_gpio.hpp"
 #include "portapack_hal.hpp"
+#include "portapack.hpp"
 
 #include "jtag_target_gpio.hpp"
 #include "cpld_max5.hpp"
@@ -30,11 +31,15 @@
 #include "portapack_cpld_data.hpp"
 #include "hackrf_cpld_data.hpp"
 
+#include "crc.hpp"
+
+#define REV_20150901_CHECKSUM 0xE0EF80FB
+#define REV_20170522_CHECKSUM 0xD1BEB722
+
 namespace portapack {
 namespace cpld {
 
-CpldUpdateStatus update_if_necessary(
+CpldUpdateStatus update_if_necessary(const Config config) {
-    const Config config) {
     jtag::GPIOTarget target{
         portapack::gpio_cpld_tck,
         portapack::gpio_cpld_tms,
@@ -87,6 +92,121 @@ CpldUpdateStatus update_if_necessary(
     return ok ? CpldUpdateStatus::Success : CpldUpdateStatus::Program_failed;
 }
 
+static CpldUpdateStatus enter_maintenance_mode(CPLD& cpld) {
+    /* Unknown state */
+    cpld.reset();
+    cpld.run_test_idle();
+
+    /* Run-Test/Idle */
+    if (!cpld.idcode_ok()) {
+        return CpldUpdateStatus::Idcode_check_failed;
+    }
+
+    cpld.sample();
+    cpld.bypass();
+    cpld.enable();
+
+    /* If silicon ID doesn't match, there's a serious problem. Leave CPLD
+     * in passive state.
+     */
+    if (!cpld.silicon_id_ok()) {
+        return CpldUpdateStatus::Silicon_id_check_failed;
+    }
+
+    return CpldUpdateStatus::Success;
+}
+
+static void exit_maintenance_mode(CPLD& cpld) {
+    cpld.disable();
+    cpld.bypass();
+
+    /* Initiate SRAM reload from flash we just programmed. */
+    cpld.sample();
+    cpld.clamp();
+    cpld.disable();
+}
+
+static uint32_t get_firmware_crc(CPLD& cpld) {
+    CRC<32> crc{0x04c11db7, 0xffffffff, 0xffffffff};
+    cpld.prepare_read(0x0000);
+
+    for (size_t i = 0; i < 3328; i++) {
+        uint16_t data = cpld.read();
+        crc.process_byte((data >> 0) & 0xff);
+        crc.process_byte((data >> 8) & 0xff);
+        crc.process_byte((data >> 16) & 0xff);
+        crc.process_byte((data >> 24) & 0xff);
+    }
+
+    cpld.prepare_read(0x0001);
+
+    for (size_t i = 0; i < 512; i++) {
+        uint16_t data = cpld.read();
+        crc.process_byte((data >> 0) & 0xff);
+        crc.process_byte((data >> 8) & 0xff);
+        crc.process_byte((data >> 16) & 0xff);
+        crc.process_byte((data >> 24) & 0xff);
+    }
+
+    return crc.checksum();
+}
+
+CpldUpdateStatus update_autodetect(const Config config_rev_20150901, const Config config_rev_20170522) {
+    jtag::GPIOTarget target{
+        portapack::gpio_cpld_tck,
+        portapack::gpio_cpld_tms,
+        portapack::gpio_cpld_tdi,
+        portapack::gpio_cpld_tdo};
+    jtag::JTAG jtag{target};
+    CPLD cpld{jtag};
+
+    if (portapack::display.read_display_status())
+        return CpldUpdateStatus::Success;  // LCD is ready
+
+    CpldUpdateStatus result = enter_maintenance_mode(cpld);
+    if (result != CpldUpdateStatus::Success)
+        return result;
+
+    uint32_t checksum = get_firmware_crc(cpld);
+
+    if (checksum == REV_20170522_CHECKSUM) {
+        // H2 firmware present
+        if (!cpld.program(config_rev_20150901.block_0, config_rev_20150901.block_1))
+            return CpldUpdateStatus::Program_failed;
+    } else if (checksum == REV_20150901_CHECKSUM) {
+        // H1 firmware present
+        if (!cpld.program(config_rev_20170522.block_0, config_rev_20170522.block_1))
+            return CpldUpdateStatus::Program_failed;
+    } else {
+        // no firmware present
+        if (!cpld.program(config_rev_20150901.block_0, config_rev_20150901.block_1))
+            return CpldUpdateStatus::Program_failed;
+    }
+
+    exit_maintenance_mode(cpld);
+
+    if (portapack::display.read_display_status())
+        return CpldUpdateStatus::Success;  // LCD is ready
+
+    if (checksum != REV_20150901_CHECKSUM && checksum != REV_20170522_CHECKSUM) {
+        // try the other one
+        CpldUpdateStatus result = enter_maintenance_mode(cpld);
+
+        if (result != CpldUpdateStatus::Success)
+            return result;
+
+        if (!cpld.program(config_rev_20170522.block_0, config_rev_20170522.block_1))
+            return CpldUpdateStatus::Program_failed;
+
+        exit_maintenance_mode(cpld);
+
+        if (portapack::display.read_display_status())
+            return CpldUpdateStatus::Success;  // LCD is ready
+    }
+
+    return CpldUpdateStatus::Program_failed;
+}
+
 } /* namespace cpld */
 } /* namespace portapack */
 

firmware/common/cpld_update.hpp

@@ -34,8 +34,8 @@ enum class CpldUpdateStatus {
     Program_failed = 3
 };
 
-CpldUpdateStatus update_if_necessary(
+CpldUpdateStatus update_if_necessary(const Config config);
-    const Config config);
+CpldUpdateStatus update_autodetect(const Config config_rev_20150901, const Config config_rev_20170522);
 
 } /* namespace cpld */
 } /* namespace portapack */

firmware/common/lcd_ili9341.cpp

@@ -84,6 +84,17 @@ void lcd_wake() {
     lcd_display_on();
 }
 
+uint32_t lcd_read_display_status() {
+    io.lcd_data_write_command_and_data(0x09, {});
+    io.lcd_read_word();
+
+    uint32_t value2 = io.lcd_read_word();
+    uint32_t value3 = io.lcd_read_word();
+    uint32_t value4 = io.lcd_read_word();
+    uint32_t value5 = io.lcd_read_word();
+    return value5 + (value4 << 8) + (value3 << 16) + (value2 << 24);
+}
+
 void lcd_init() {
     // LCDs are configured for IM[2:0] = 001
     // 8080-I system, 16-bit parallel bus
@@ -260,6 +271,25 @@ void lcd_vertical_scrolling_start_address(
 
 }  // namespace
 
+bool ILI9341::read_display_status() {
+    lcd_reset();
+    uint32_t display_status = lcd_read_display_status();
+
+    /* This tries to validate the display_status.
+     * The value could vary from device to device, so we are less specific here.
+     * 0xFFFFFEFF was seen when the display was not reachable
+     * 0x00610000 was seen when the display was reachable
+     */
+
+    if (display_status > 0x0E000000ULL)
+        return false;
+
+    if (display_status < 0x00000100ULL)
+        return false;
+
+    return true;
+}
+
 void ILI9341::init() {
     lcd_reset();
     lcd_init();

firmware/common/lcd_ili9341.hpp

@@ -42,6 +42,8 @@ class ILI9341 {
     ILI9341(ILI9341&&) = delete;
     void operator=(const ILI9341&) = delete;
 
+    bool read_display_status();
+
     void init();
     void shutdown();
 

firmware/common/portapack_persistent_memory.cpp

@@ -430,13 +430,15 @@ void defaults() {
 }
 
 void init() {
-    const auto switches_state = get_switches_state();
+    const auto switches_state = swizzled_switches();
 
     // ignore for valid check
     auto config_mode_backup = config_mode_storage_direct();
     set_config_mode_storage_direct(CONFIG_MODE_NORMAL_VALUE);
 
-    if (!(switches_state[(size_t)ui::KeyEvent::Left] && switches_state[(size_t)ui::KeyEvent::Right]) && backup_ram->is_valid()) {
+    if (!(((switches_state >> (size_t)ui::KeyEvent::Left & 1) == 1) &&
+          ((switches_state >> (size_t)ui::KeyEvent::Right & 1) == 1)) &&
+        backup_ram->is_valid()) {
         // Copy valid persistent data into cache.
         cached_backup_ram = *backup_ram;