commit bc5fcd5c7807649f078282031bf1bbc5220ff487
Author: Arne Zachlod <arne@nerdkeller.org>
Date:   Thu Feb 13 18:52:30 2025 +0100

    first working version

diff --git a/sdlogger.py b/sdlogger.py
new file mode 100755
index 0000000..9e8cc7d
--- /dev/null
+++ b/sdlogger.py
@@ -0,0 +1,103 @@
+#! /usr/bin/python
+
+import os, vfs
+import time
+
+from machine import UART
+from machine import SPI
+from machine import Pin
+from sdcard import SDCard
+
+BUFSIZE_BUFFER = const(49 * 1024)
+BUFSIZE_RXBUF = const(32 * 1024)
+BUF_THRESHOLD = const(16 * 1024)
+UART_TIMEOUT = const(1000) # timeout to start writing in ms
+BUFFER = bytearray(BUFSIZE_BUFFER)
+BUF_POS = 0
+SD_MOUNT = '/sd'
+LOG_FOLDER = 'logs'
+LOG_FILENAME = 'logfile.log'
+LOG_PATH = SD_MOUNT + '/' + LOG_FOLDER + '/' + LOG_FILENAME
+WRITETIME = time.ticks_ms()
+
+UART0 = UART(0, baudrate=115200, rx=20, tx=21, rxbuf=BUFSIZE_RXBUF)
+SDSPI = SPI(1,
+            baudrate=40000000,
+            polarity=0,
+            phase=0,
+            bits=8,
+            firstbit=SPI.MSB,
+            sck=Pin(6),
+            mosi=Pin(2),
+            miso=Pin(4))
+SD = SDCard(SDSPI, Pin(9, Pin.OUT))
+
+
+def sdcard_init():
+    """sdcard setup, mounting and creating logfile and folder"""
+    os.mount(SD, SD_MOUNT)
+    dirls = os.listdir(SD_MOUNT)
+    if not LOG_FOLDER in dirls:
+        os.mkdir(SD_MOUNT + '/' + LOG_FOLDER)
+    # find the new filename for LOG_FILENAME. eg: foo.log23
+    dirls = os.listdir(SD_MOUNT + '/' + LOG_FOLDER)
+    x = -1
+    for file in dirls:
+        tmpstr = ''.join(filter(str.isdigit, file))
+        if tmpstr:
+            tmp = int(tmpstr)
+            if tmp > x :
+                x = tmp
+    global LOG_FILENAME
+    global LOG_PATH
+    LOG_FILENAME = LOG_FILENAME + str(x+1)
+    LOG_PATH = SD_MOUNT + '/' + LOG_FOLDER + '/' + LOG_FILENAME
+
+def writebuf():
+    """ write buffer to SDcard """
+    global BUF_POS
+    global WRITETIME
+    global LOG_PATH
+    dbg_tmr = time.ticks_ms()
+    fd = open(LOG_PATH, "ab")
+    mv = memoryview(BUFFER)
+    fd.write(mv[:BUF_POS])
+    fd.flush()
+    fd.close()
+    diff_tmr = time.ticks_diff(time.ticks_ms(), dbg_tmr)
+    print(f"SD write time: {diff_tmr} ms for {BUF_POS} bytes")
+    BUF_POS = 0
+    WRITETIME = time.ticks_ms()
+
+
+def readuart():
+    mv = memoryview(BUFFER)
+    global BUF_POS
+    global BUFSIZE_RXBUF
+    global BUFSIZE_BUFFER
+    if (BUF_POS + BUFSIZE_RXBUF) < (BUFSIZE_BUFFER - 1024):
+        num = UART0.readinto(mv[BUF_POS : BUF_POS + BUFSIZE_RXBUF])
+    else:
+        num = UART0.readinto(mv[BUF_POS : BUFSIZE_BUFFER - 1024])
+    BUF_POS = BUF_POS + num
+    if (num >= BUFSIZE_RXBUF) or (BUF_POS >= BUFSIZE_BUFFER - 1024):
+        tmp = str.encode("\r\nsdlogger: buffer was full\r\n")
+        mv[BUF_POS:BUF_POS+len(tmp)] = tmp
+
+
+def control():
+    """main control loop"""
+    if UART0.any():
+        # read UART if any characters available
+        readuart()
+    if (BUF_POS > BUF_THRESHOLD) or (BUF_POS > 0 and (1000 < time.ticks_diff(time.ticks_ms(), WRITETIME))):
+        # write log if no UART transfer for more than WRITETIME seconds or buffer is fuller than BUF_THRESHOLD
+        writebuf()
+
+def main():
+    sdcard_init()
+    while True:
+        control()
+
+main()
+