2 files changed, 136 insertions, 0 deletions
diff --git a/CODE/debugprewk/debug/comm/spi/arduino_spi_master/arduino_spi_master.ino b/CODE/debugprewk/debug/comm/spi/arduino_spi_master/arduino_spi_master.ino
new file mode 100644
index 0000000..248ef0f
--- /dev/null
+++ b/CODE/debugprewk/debug/comm/spi/arduino_spi_master/arduino_spi_master.ino
@@ -0,0 +1,34 @@
+#include <SPI.h>
+#define SS_PIN 10
+#define BAUD_RATE 19200
+#define CHAR_BUF 128
+
+void setup() {
+  pinMode(SS_PIN, OUTPUT);
+  Serial.begin(BAUD_RATE);
+  SPI.begin();
+  SPI.setBitOrder(MSBFIRST);
+  SPI.setClockDivider(SPI_CLOCK_DIV16);
+  SPI.setDataMode(SPI_MODE0);
+  delay(1000); // Give the OpenMV Cam time to bootup.
+}
+
+void loop() {
+  int32_t len = 0;
+  char buff[CHAR_BUF] = {0};
+  digitalWrite(SS_PIN, LOW);
+  delay(1); // Give the OpenMV Cam some time to setup to send data.
+
+  if(SPI.transfer(1) == 85) { // saw sync char?
+    SPI.transfer(&len, 4); // get length
+    if (len) {
+      SPI.transfer(&buff, min(len, CHAR_BUF));
+      len -= min(len, CHAR_BUF);
+    }
+    while (len--) SPI.transfer(0); // eat any remaining bytes
+  }
+
+  digitalWrite(SS_PIN, HIGH);
+  Serial.print(buff);
+  delay(1); // Don't loop to quickly.
+}
+\ No newline at end of file
diff --git a/CODE/debugprewk/debug/comm/spi/arduino_spi_slave_1.py b/CODE/debugprewk/debug/comm/spi/arduino_spi_slave_1.py
new file mode 100644
index 0000000..e05c2f0
--- /dev/null
+++ b/CODE/debugprewk/debug/comm/spi/arduino_spi_slave_1.py
@@ -0,0 +1,102 @@
+# This work is licensed under the MIT license.
+# Copyright (c) 2013-2023 OpenMV LLC. All rights reserved.
+# https://github.com/openmv/openmv/blob/master/LICENSE
+#
+# SPI with the Arduino as the master device and the OpenMV Cam as the slave.
+#
+# Please wire up your OpenMV Cam to your Arduino like this:
+#
+# OpenMV Cam Master Out Slave In (P0) - Arduino Uno MOSI (11)
+# OpenMV Cam Master In Slave Out (P1) - Arduino Uno MISO (12)
+# OpenMV Cam Serial Clock        (P2) - Arduino Uno SCK  (13)
+# OpenMV Cam Slave Select        (P3) - Arduino Uno SS   (10)
+# OpenMV Cam Ground                   - Arduino Ground
+
+import pyb
+import ustruct
+import time
+
+text = "Hello World!\n"
+data = ustruct.pack("<bi%ds" % len(text), 85, len(text), text)  # 85 is a sync char.
+# Use "ustruct" to build data packets to send.
+# "<" puts the data in the struct in little endian order.
+# "b" puts a signed char in the data stream.
+# "i" puts a signed integer in the data stream.
+# "%ds" puts a string in the data stream. E.g. "13s" for "Hello World!\n" (13 chars).
+# See https://docs.python.org/3/library/struct.html
+
+# READ ME!!!
+#
+# Please understand that when your OpenMV Cam is not the SPI master it may miss responding to
+# sending data as a SPI slave no matter if you call "spi.send()" in an interrupt callback or in the
+# main loop below. Because of this you must absolutely design your communications protocol such
+# that if the slave device (the OpenMV Cam) doesn't call "spi.send()" in time that garbage data
+# read from the SPI peripheral by the master (the Arduino) is tossed. To accomplish this we use a
+# sync character of 85 (binary 01010101) which the Arduino will look for as the first byte read.
+# If it doesn't see this then it aborts the SPI transaction and will try again. Second, in order to
+# clear out the SPI peripheral state we always send a multiple of four bytes and an extra four zero
+# bytes to make sure that the SPI peripheral doesn't hold any stale data which could be 85. Note
+# that the OpenMV Cam will miss the "spi.send()" window randomly because it has to service
+# interrupts. Interrupts will happen a lot more while connected to your PC.
+
+# The hardware SPI bus for your OpenMV Cam is always SPI bus 2.
+# polarity = 0 -> clock is idle low.
+# phase = 0 -> sample data on rising clock edge, output data on falling clock edge.
+spi = pyb.SPI(2, pyb.SPI.SLAVE, polarity=0, phase=0)
+
+
+# NSS callback.
+def nss_callback(line):
+    global spi, data
+    try:
+        spi.send(data, timeout=1000)
+    except OSError as err:
+        pass  # Don't care about errors - so pass.
+        # Note that there are 3 possible errors. A timeout error, a general purpose error, or
+        # a busy error. The error codes are 116, 5, 16 respectively for "err.arg[0]".
+
+
+# Configure NSS/CS in IRQ mode to send data when requested by the master.
+pyb.ExtInt(pyb.Pin("P3"), pyb.ExtInt.IRQ_FALLING, pyb.Pin.PULL_UP, nss_callback)
+
+while True:
+    time.sleep_ms(1000)
+
+###################################################################################################
+# Arduino Code
+###################################################################################################
+#
+# #include <SPI.h>
+# #define SS_PIN 10
+# #define BAUD_RATE 19200
+# #define CHAR_BUF 128
+#
+# void setup() {
+#   pinMode(SS_PIN, OUTPUT);
+#   Serial.begin(BAUD_RATE);
+#   SPI.begin();
+#   SPI.setBitOrder(MSBFIRST);
+#   SPI.setClockDivider(SPI_CLOCK_DIV16);
+#   SPI.setDataMode(SPI_MODE0);
+#   delay(1000); // Give the OpenMV Cam time to bootup.
+# }
+#
+# void loop() {
+#   int32_t len = 0;
+#   char buff[CHAR_BUF] = {0};
+#   digitalWrite(SS_PIN, LOW);
+#   delay(1); // Give the OpenMV Cam some time to setup to send data.
+#
+#   if(SPI.transfer(1) == 85) { // saw sync char?
+#     SPI.transfer(&len, 4); // get length
+#     if (len) {
+#       SPI.transfer(&buff, min(len, CHAR_BUF));
+#       len -= min(len, CHAR_BUF);
+#     }
+#     while (len--) SPI.transfer(0); // eat any remaining bytes
+#   }
+#
+#   digitalWrite(SS_PIN, HIGH);
+#   Serial.print(buff);
+#   delay(1); // Don't loop to quickly.
+# }