Added readme

README.md

@@ -1,2 +1,23 @@
 OpenModem
 ==========
+
+OpenModem is an open source firmware implementation of a AFSK modem supporting 300, 1200 and 2400 baud operation, suitable for communication over a wide variety of analogue mediums, both radio and wired. The firmware is designed for and compatible with [unsigned.io's OpenModem](https://unsigned.io/openmodem), but can be used on any similar build.
+
+Complete modems are available from [the unsigned.io shop](http://unsigned.io/shop), or can be build from scratch by referring to the schematics and documentation on the [OpenModem page](https://unsigned.io/openmodem)
+
+## A few highlights
+
+- 300, 1200 and 2400 baud operation
+- Full KISS TNC compatibility
+- Secure in-modem AES-128 encryption
+- SD card support
+- Packet logging in PCAP format (WireShark compatible)
+- Digitally adjustable input and output gain control
+- Easy to use graphical config utility
+- Supports standard GPS and bluetooth modules
+- Supports large packets, 576 byte MTU
+- Very large in-modem packet queue
+
+## Usage
+
+Please refer to the manual and instructions posted at the [OpenModem page](https://unsigned.io/openmodem). The default serial connection settings are 115200 baud, 8N1. For configuring the modem, please see the OpenModem Config Utility.

device.h

@@ -34,7 +34,7 @@
 #define CONFIG_BENCHMARK_MODE false
 
 // CSMA Settings
-#define CONFIG_FULL_DUPLEX false  // TODO: Actually implement fdx
+#define CONFIG_FULL_DUPLEX false
 #define CONFIG_CSMA_P_DEFAULT 255
 #define CONFIG_CSMA_SLOTTIME_DEFAULT 20
 
@@ -42,7 +42,10 @@
 #define AX25_MAX_FRAME_LEN 611
 #define AX25_MAX_PAYLOAD   576
 #define AX25_MIN_PAYLOAD   2
-#define AX25_ENCRYPTED_MIN_LENGTH 51 // Padding byte + IV + 1 Block + HMAC + CRC
+#define AX25_ENCRYPTED_MIN_LENGTH 51
+// The minimum packet length of an AES-128
+// encrypted packet is equal to:
+// padding byte + IV + 1 Block + HMAC + CRC
 
 // Packet settings
 #define CONFIG_PASSALL false

hardware/AFSK.h

@@ -9,7 +9,6 @@
 #include "util/FIFO.h"
 #include "protocol/HDLC.h"
 
-// TODO: Optimise RAM by moving this to progmem
 #define SIN_LEN 512
 static const uint8_t sine_table[] =
 {
@@ -98,7 +97,7 @@ inline static uint8_t sinSample(uint16_t i) {
     #define PHASE_BITS   8 // Sub-sample phase counter resolution
 #endif
 
-#define PHASE_INC    1                              // Nudge by above resolution for each adjustment
+#define PHASE_INC    1     // Nudge by above resolution for each adjustment
 
 
 #define PHASE_MAX    (ADC_SAMPLESPERBIT * PHASE_BITS)   // Size of our phase counter