implement software-based aux uart

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "firmware/lib/harp.core.rp2040"]
 	path = firmware/lib/harp.core.rp2040
 	url = [email protected]:AllenNeuralDynamics/harp.core.rp2040.git
+[submodule "firmware/lib/pico.async-uart"]
+	path = firmware/lib/pico.async-uart
+	url = [email protected]:AllenNeuralDynamics/pico.async-uart.git

firmware/CMakeLists.txt

@@ -8,6 +8,8 @@ add_definitions(-DGIT_HASH="${COMMIT_ID}") # Usable in source code.
 #add_definitions(-DDEBUG) # Uncomment for debugging
 
 
+#set(PICO_PLATFORM rp2040) # rp2040 is the default.
+
 # PICO_SDK_PATH must be defined.
 include(${PICO_SDK_PATH}/pico_sdk_init.cmake)
 
@@ -23,10 +25,7 @@ project(white_rabbit)
 pico_sdk_init()
 
 add_subdirectory(lib/harp.core.rp2040/firmware) # Path to harp.core.rp2040.
-
-add_library(uart_nonblocking
-    src/uart_nonblocking.cpp
-)
+add_subdirectory(lib/pico.async-uart) # Path to uart_nonblocking and soft_uart
 
 add_library(white_rabbit_app
     src/white_rabbit_app.cpp
@@ -38,12 +37,12 @@ add_executable(${PROJECT_NAME}
 
 include_directories(inc)
 
-target_link_libraries(uart_nonblocking hardware_dma hardware_timer pico_stdlib)
 target_link_libraries(white_rabbit_app harp_core harp_c_app harp_sync
-                      hardware_divider pico_stdlib uart_nonblocking hardware_dma)
+                      hardware_divider pico_stdlib uart_nonblocking pio_uart
+                      hardware_pio hardware_dma soft_uart)
 
 target_link_libraries(${PROJECT_NAME} harp_core harp_c_app harp_sync pico_stdlib
-                      hardware_dma hardware_timer uart_nonblocking
+                      hardware_dma hardware_timer uart_nonblocking pio_uart
                       white_rabbit_app)
 
 pico_add_extra_outputs(${PROJECT_NAME})

firmware/README.md

@@ -12,7 +12,7 @@ This project uses the [Pico SDK](https://github.com/raspberrypi/pico-sdk/tree/ma
 The SDK needs to be downloaded and installed to a known folder on your PC.
 Note that the PICO SDK also contains submodules (including TinyUSB), so you must ensure that they are also fetched with:
 ````
-git clone git clone git@github.com:raspberrypi/pico-sdk.git
+git clone [email protected]:raspberrypi/pico-sdk.git
 git submodule update --init --recursive
 ````
 

firmware/inc/config.h

@@ -40,8 +40,7 @@
 #define MAX_AUX_SYNC_BAUDRATE (1'000'000UL) // Aux Baud rate should be slower
                                             // than this value.
 #define AUX_PIN (0)
-#define AUX_SYNC_START_OFFSET_US (0) // Offset from spec to account for fixed
-                                      // delays before transmission starts.
+#define AUX_SYNC_START_OFFSET_US (0)
 
 #define LED0_PIN (24)
 #define LED1_PIN (25)

firmware/inc/white_rabbit_app.h

@@ -10,6 +10,7 @@
 #include <harp_c_app.h>
 #include <harp_synchronizer.h>
 #include <uart_nonblocking.h>
+#include <soft_uart.h>
 #include <core_registers.h>
 #include <pico/divider.h> // for fast hardware division.
 #ifdef DEBUG

firmware/src/white_rabbit_app.cpp

@@ -33,10 +33,14 @@ volatile uint32_t __not_in_flash("double_buffers") aux_clkout_seconds_b;
 volatile uint32_t __not_in_flash("double_buffers") *dispatch_second;
 volatile uint32_t __not_in_flash("double_buffers") *load_second;
 
+// AUX CLKout software implementation.
+SoftUART soft_uart = SoftUART(AUX_PIN);
+
 // PPS Alarm/IRQ resources
 int32_t __not_in_flash("double_buffers") pps_output_alarm_num = -1;
 uint32_t __not_in_flash("double_buffers") pps_output_irq_number;
 
+
 void setup_harp_clkout()
 {
     // Setup DMA.
@@ -131,22 +135,16 @@ void __not_in_flash_func(dispatch_and_reschedule_harp_clkout)()
     timer_hw->inte |= (1u << harp_clkout_alarm_num);
     // Arm alarm by writing the alarm time.
     timer_hw->alarm[harp_clkout_alarm_num] = alarm_time_us;
-
 }
 
 void setup_aux_clkout()
 {
     // Setup DMA.
     if (aux_clkout_dma_chan < 0) // Claim a DMA channel if not yet claimed.
         aux_clkout_dma_chan = dma_claim_unused_channel(true);
-    // Setup GPIO Pins.
-    // Setup UART TX for periodic transmission of the time.
-    uart_inst_t* aux_uart_id = AUX_SYNC_UART;
-    uart_init(aux_uart_id, app_regs.AuxBaudRate);
-    uart_set_hw_flow(aux_uart_id, false, false);
-    uart_set_fifo_enabled(aux_uart_id, false); // Set FIFO size to 1.
-    uart_set_format(aux_uart_id, 8, 1, UART_PARITY_NONE);
-    gpio_set_function(AUX_PIN, GPIO_FUNC_UART);
+    // Update baud rate (if it has changed).
+    soft_uart.reset();
+    soft_uart.set_baud_rate(app_regs.AuxBaudRate);
     // Setup AUX CLKOUT periodic outgoing time message.
     // Setup Outgoing msg double buffer;
     dispatch_second = &aux_clkout_seconds_a;
@@ -169,7 +167,7 @@ void setup_aux_clkout()
     *dispatch_second = curr_harp_seconds + 1;
     uint64_t next_msg_harp_time_us = (uint64_t(curr_harp_seconds) * 1'000'000UL)
                                      + 1'000'000UL;
-    // Apply offset if any.
+    // Apply additional offset if any.
     next_msg_harp_time_us += AUX_SYNC_START_OFFSET_US;
     // Schedule next time msg dispatch in system time.
     // Low-level interface (fast!) to re-schedule this function.
@@ -183,8 +181,8 @@ void setup_aux_clkout()
 void __not_in_flash_func(dispatch_and_reschedule_aux_clkout)()
 {
     // Dispatch the previously-configured time.
-    dispatch_uart_stream(aux_clkout_dma_chan, AUX_SYNC_UART,
-                         (uint8_t*)dispatch_second, sizeof(dispatch_second));
+    soft_uart.send((uint8_t*)dispatch_second, sizeof(dispatch_second));
+
     // Clear the latched hardware interrupt.
     timer_hw->intr = (1u << aux_clkout_alarm_num);
     // Compute the *next* whole harp time second.
@@ -230,7 +228,7 @@ void cleanup_aux_clkout()
     irq_set_enabled(aux_clkout_irq_number, false);
     irq_remove_handler(aux_clkout_irq_number,
                        dispatch_and_reschedule_aux_clkout);
-    uart_deinit(AUX_SYNC_UART);
+    soft_uart.cleanup();
     gpio_deinit(AUX_PIN);
 }
 
@@ -415,6 +413,8 @@ void write_aux_baud_rate(msg_t& msg)
 
 void update_app_state()
 {
+    if (soft_uart.requires_update())
+        soft_uart.update();
     // Update the state of ConnectedDevices.
     uint16_t old_port_raw = app_regs.ConnectedDevices;
     uint32_t port_raw = gpio_get_all();

software/pyharp/enable_aux_uart.py

@@ -16,8 +16,8 @@ class Regs(Enum):
     AuxPortBaudRate = 36    # U32
 
 
-#BAUDRATE = 115200
-BAUDRATE = 9600
+BAUDRATE = 115200
+#BAUDRATE = 9600
 #BAUDRATE = 1000
 
 # Open the device and print the info on screen