add shrike-ctl utility : flasher utility for fpga from host PC (#21)

* add shrike-ctl utility

 -Raised the serial transfer chunk size from 64 bytes to the full .bin size.
 -Transfer time results (file size: 46,408 bytes):
 -64-byte chunks  → ~10.7 seconds
 -full-file chunk(46,408-byte) → ~3.5 seconds

Author: GaikwadPrasad

utils/shrike-ctl/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.13)
+include(/PATH/TO/PICO_SDK/pico_sdk_import.cmake)
+project(shrike-ctl)
+pico_sdk_init()
+add_executable(shrike-ctl main.c)
+target_link_libraries(shrike-ctl 
+        pico_stdlib 
+        hardware_spi
+    )
+pico_enable_stdio_usb(shrike-ctl 1)
+pico_add_extra_outputs(shrike-ctl) 

utils/shrike-ctl/README.md

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+# Shrike-ctl
+
+A utility to program the FPGA on the Shrike development board directly from your PC.
+
+## Overview
+
+The flashing utility uses these key files:
+
+1. `shrike-ctl.py` – Python host-side tool running on the PC to send the FPGA bitstream over a serial port.  
+2. `shrike-ctl.uf2` – Prebuilt firmware image for the RP2040 MCU on board Shrike ; when flashed, it turns the board into an FPGA programmer.
+
+## Prerequisite: Flashing the UF2 Firmware
+
+### Drag-and-drop UF2
+
+- Put Shrike in BOOTSEL mode (hold BOOTSEL while plugging in USB).  
+- A USB mass-storage device appears on the PC.  
+- Drag and drop `shrike-ctl.uf2` which can be found [here](./shrike-ctl.uf2) onto this drive. 
+- The board reboots and now runs the FPGA flasher firmware. 
+- This method uses the provided `.uf2` built from `shrike-ctl.c` and `CMakeLists.txt`. 
+
+
+## Programming the FPGA from PC
+
+Once the board is running the shrike-ctl firmware, the FPGA can be  programmed from the PC using `shrike-ctl.py`.
+
+### Requirements
+
+1. Python version 3.12 or above installed on the host PC.  
+2. `shrike-ctl.py` script.  
+3. FPGA bitstream file generated by your FPGA tools.
+
+### Usage
+
+Execute the Python script with arguments for the serial port and bitstream path, 
+
+for example:
+
+```
+python shrike-ctl.py <PORT> <BitstreamFilePath>`
+```
+
+Where:
+
+- `<PORT>` is the serial port name (e.g., `COM5` on Windows, `/dev/ttyACM0` or `/dev/ttyUSB0` on Linux).  
+- `<BitstreamFilePath>` is the path to your FPGA bitstream file.
+
+### Build guide
+```note
+In your CMakeLists.txt file, update the path to pico-sdk.
+Replace your path at `include(/PATH/TO/PICO_SDK/pico_sdk_import.cmake)`
+```
+Download `PICO-SDK` [here](https://github.com/raspberrypi/pico-sdk/blob/master/README.md)

utils/shrike-ctl/main.c

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+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "hardware/spi.h"
+
+// -----------------SPI Definaltions-----------------------------
+#define SPI_INSTANCE (spi0) 	// SPI0  
+#define SPI_CLOCK (1000*16000)  // FPGA support 16MHZ clock
+#define PIN_MISO  0             // Not used (receive only)
+#define PIN_MOSI  3
+#define PIN_SCK   2
+#define PIN_SS    1
+#define PIN_PWR   12            // Power PIN
+#define PIN_EN    13           // Enable PIN
+#define BUF_SIZE  64
+uint8_t tx_buf[BUF_SIZE];
+size_t  tx_len = 0;
+
+int main(){
+    stdio_init_all();
+    //---------------------SPI PIN Setup------------------------------------
+    spi_init(SPI_INSTANCE, SPI_CLOCK);
+    gpio_set_function(PIN_MISO, GPIO_FUNC_SPI);
+    gpio_set_function(PIN_MOSI, GPIO_FUNC_SPI);
+    gpio_set_function(PIN_SCK,  GPIO_FUNC_SPI);
+    gpio_set_function(PIN_SS, GPIO_FUNC_SPI);
+
+    //--------------------- PIN Initilization--------------------------------
+    gpio_init(PIN_SS);
+    gpio_init(PIN_PWR);
+    gpio_init(PIN_EN);
+
+    //-----------------------PINS Set as a output----------------------------
+    gpio_set_dir(PIN_PWR, GPIO_OUT);
+    gpio_set_dir(PIN_EN, GPIO_OUT);
+    gpio_set_dir(PIN_SS, GPIO_OUT);
+
+    //----------------------FPGA RESET---------------------------------------
+    gpio_put(PIN_PWR, 0);
+    gpio_put(PIN_EN, 0);
+    gpio_put(PIN_SS, 1);
+    sleep_ms(3);
+
+    //--------------------FPGA Initilization---------------------------------
+    gpio_put(PIN_PWR, 1);
+    gpio_put(PIN_EN, 1);
+    gpio_put(PIN_SS, 0);
+    sleep_ms(3);
+    gpio_put(PIN_SS, 1);
+    sleep_us(3);
+
+    while (true) {
+    
+         int ch = getchar_timeout_us(1000);
+           if (ch >= 0 && ch <= 255){
+      	        tx_buf[tx_len++] = (uint8_t)ch;
+
+	         if (tx_len == BUF_SIZE){
+                      gpio_put(PIN_SS, 0);
+                      spi_write_blocking(SPI_INSTANCE, tx_buf, tx_len);
+                      gpio_put(PIN_SS, 1);
+                      tx_len = 0;
+                  }
+            }
+      }
+}    

utils/shrike-ctl/shrike-ctl.py

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+import serial
+import time
+import os
+import sys
+
+#Configuration Setup
+if len(sys.argv) > 1:
+    PORT = sys.argv[1]
+else:
+    PORT = input("Enter serial port (e.g., /dev/ttyACM0 or COM3): ").strip()
+
+BAUDRATE = 115200  # Match Shrike Baud Rate
+CHUNK_SIZE = 46408 # Size of Bitstream
+
+if len(sys.argv) > 2:
+    file_paths = sys.argv[2:]
+else:
+    FILE_PATH = input("Enter firmware file path : ").strip()
+    file_paths = [FILE_PATH]
+
+for FILE_PATH in file_paths:
+    if not os.path.exists(FILE_PATH):
+        print(f" Error: File not found: {FILE_PATH}")
+        continue
+    if os.path.isdir(FILE_PATH):
+        print(f" Error: '{FILE_PATH}' is a DIRECTORY!")
+        continue
+    if not os.path.isfile(FILE_PATH):
+        print(f" Error: '{FILE_PATH}' is not a file")
+        continue
+    
+file_size = os.path.getsize(FILE_PATH)
+print(f" Uploading: {os.path.basename(FILE_PATH)} ({file_size} bytes)")
+
+ser = serial.Serial(PORT, BAUDRATE, timeout=1, rtscts=False, dsrdtr=False)
+file_size = os.path.getsize(FILE_PATH)
+print(f"File size: {file_size} bytes")
+sent = 0
+with open(FILE_PATH, "rb") as file:
+    while sent < file_size:
+        data = file.read(CHUNK_SIZE)
+        if not data:
+              break
+        ser.write(data)
+        sent += len(data)
+        print(f"Sent {sent}/{file_size} bytes", end='\r')
+        time.sleep(0.01)  # 10ms delay
+
+print(f"\nFile transfer complete. Total: {sent} bytes")
+ser.close()