Earle F. Philhower, III
fca7fb5e0f
SingleFileDisk allows for exporting a file from the onboard LittleFS filesystem to a PC through an emulated FAT drive when connected. The PC can open and copy the file, as well as delete it, but the PC has no access to the main onboard LittleFS and no actual on-flash FAT structures are used. This is handy for things like data loggers. They can run connected to USB power for some time, and then connected to a PC to dowmload the CSV log recorded. It's almost 2023, allow LFN (long file names) on the emulated USB disk. Reduce the disk buffer size to 64 bytes. The buffer is statically allocated so it's always present, even in non-USB disk mode, meaning all apps will pay the RAM price for it. 64 bytes is slower to read but works and saves ~1/2KB of heap for all apps.
93 lines
2.2 KiB
Arduino
93 lines
2.2 KiB
Arduino
// Simple logger with USB upload to PC
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// Uses SingleFileDrive to export an onboard LittleFS file to the computer
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// The PC can open/copy the file, and then the user can delete it to restart
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// Released to the public domain, 2022 - Earle F. Philhower, III
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#include <SingleFileDrive.h>
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#include <LittleFS.h>
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uint32_t cnt = 0;
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bool okayToWrite = true;
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// Make the CSV file and give it a simple header
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void headerCSV() {
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File f = LittleFS.open("data.csv", "w");
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f.printf("sample,millis,temp,rand\n");
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f.close();
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cnt = 0;
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}
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// Called when the USB stick connected to a PC and the drive opened
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// Note this is from a USB IRQ so no printing to SerialUSB/etc.
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void plug(uint32_t i) {
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(void) i;
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okayToWrite = false;
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}
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// Called when the USB is ejected or removed from a PC
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// Note this is from a USB IRQ so no printing to SerialUSB/etc.
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void unplug(uint32_t i) {
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(void) i;
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okayToWrite = true;
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}
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// Called when the PC tries to delete the single file
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// Note this is from a USB IRQ so no printing to SerialUSB/etc.
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void deleteCSV(uint32_t i) {
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(void) i;
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LittleFS.remove("data.csv");
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headerCSV();
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}
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void setup() {
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Serial.begin();
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delay(5000);
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LittleFS.begin();
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// Set up the USB disk share
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singleFileDrive.onDelete(deleteCSV);
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singleFileDrive.onPlug(plug);
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singleFileDrive.onUnplug(unplug);
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singleFileDrive.begin("data.csv", "Recorded data from the Raspberry Pi Pico.csv");
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// Find the last written data
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File f = LittleFS.open("data.csv", "r");
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if (!f || !f.size()) {
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cnt = 1;
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headerCSV();
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} else {
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if (f.size() > 2048) {
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f.seek(f.size() - 1024);
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}
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do {
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String s = f.readStringUntil('\n');
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sscanf(s.c_str(), "%lu,", &cnt);
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} while (f.available());
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f.close();
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cnt++;
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}
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Serial.printf("Starting acquisition at %d\n", cnt);
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}
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void loop() {
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float temp = analogReadTemp();
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uint32_t hwrand = rp2040.hwrand32();
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// Make sure the USB connect doesn't happen while we're writing!
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noInterrupts();
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if (okayToWrite) {
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Serial.printf("Sampling...%lu\n", cnt);
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// Don't want the USB to connect during an update!
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File f = LittleFS.open("data.csv", "a");
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if (f) {
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f.printf("%lu,%lu,%f,%lu\n", cnt++, millis(), temp, hwrand);
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f.close();
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}
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}
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interrupts();
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delay(10000);
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}
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