update readme

README.md

@@ -1,3 +1,94 @@
 # cat-tracker
 
 A multi-function application designed to run on a pi node. When used in a mesh network, this app will help track your cat with a CC2500 based radio collar, using complementary CC2500 based radio modules interfaced with your Pi. 
+
+The implementation here uses CC2500 register values which intend to mimic my [Girafus M07A](https://www.girafus.com/en-en/collections/peilsender/products/ersatzteil-basismodul-fur-girafus%C2%AE-pro-track-tor-katzen-hunde-haustier-kleintier-sucher) unit. This unit is paired with my associated [tracker](https://www.girafus.com/en-en/collections/peilsender/products/extra-sender-tag-fur-den-girafus%C2%AE-pro-track-tor-haustier-hund-katze-kleintier-finder-sucher-ortung) 
+
+## CC2500 datasheet 
+[cc2500.pdf](./cc2500.pdf)
+
+## CC2500 to Raspberry Pi GPIO Pin Mapping
+
+| CC2500 Pin | Function Description                                 | Raspberry Pi GPIO Pin         | GPIO Number |
+|------------|------------------------------------------------------|-------------------------------|-------------|
+| GND        | Ground                                               | Pin 6                         | -           |
+| VCC        | 3.3V Power (⚠️ **Do not use 5V**)                     | Pin 1 or Pin 17               | -           |
+
+### SPI Connections
+
+| CC2500 Pin | Function | Raspberry Pi GPIO Pin         | GPIO Number |
+|------------|----------|-------------------------------|-------------|
+| SI         | MOSI     | Pin 19                        | GPIO 10     |
+| SCK        | SCLK     | Pin 23                        | GPIO 11     |
+| CSN        | CE0 (Chip Select) | Pin 24              | GPIO 8      |
+| SO         | MISO     | Pin 21                        | GPIO 9      |
+
+### Optional Pins
+
+| CC2500 Pin | Function                                  | Raspberry Pi GPIO Pin         | GPIO Number |
+|------------|-------------------------------------------|-------------------------------|-------------|
+| GDO0       | Interrupt/Data Ready                      | Pin 12                        | GPIO 18     |
+| GDO2       | Additional Interrupt/Data Line            | Pin 22                        | GPIO 25     |
+
+### Power Amplifier Pins (If Applicable)
+
+| CC2500 Pin | Function                                  | Raspberry Pi GPIO Pin         | Notes                                  |
+|------------|-------------------------------------------|-------------------------------|----------------------------------------|
+| PA_EN      | Control Power Amplifier (Optional)        | Any GPIO Pin                  | Connect if amplifier control is needed |
+| PA_EX      | Reserved                                  | Not Connected                 | Only connect if required               |
+
+## Reverse Engineering the Registers
+
+### SmartRF Studio
+
+#### Install
+[SmartRF Studio](https://www.ti.com/tool/SMARTRFTM-STUDIO#downloads) will automatically generate a configuration for the CC2500 Radio based on some RF parameters
+* A free registration and login is required to download this app from Texas Instruments
+* The app seems to run well via `wine` on linux. I chose to install it on an actual Windows OS, then copy the binaries.
+
+#### Copy Register JSON template
+When this is installed, copy the code export json file to help export the initial register configuration in a JSON format
+
+```bash
+cp srfexp_json.xml "~/Documents/Texas Instruments/SmartRF Studio v7/codeexport/."
+# Example copy command for linux+wine 
+```
+
+#### Understanding necessary RF Parameters
+In SmartRF Studio, open the CC2500 Device Controller under the 2.4 GHZ list.
+
+At the time of writing, it is believed this device uses 250 kBaud MSK encoding. We will choose this option.
+
+Next we need to figure out the Base Frequency, Channel numbers, and Channel Spacing
+![smart_rf](./images/smart_rf.png)
+
+### Singal Capture
+I have captured the initial signal emitted by the handheld unit when it is first powered on. To do this, I have used a HackRF SDR + gqrx application on linux.
+
+The known frequency range is 2400 – 2483.5 MHz, and my SDR has a 20 MHZ bandwidth. I choose sweep for signals by tuning the following frequencies
+| Sweep # | Center Frequency | Center Frequency (kHz) | Approx. Coverage (MHz) | Approx. Coverage (kHz)     |
+|---------|------------------|-------------------------|-------------------------|-----------------------------|
+| 1       | 2410 MHz         | 2,410,000 kHz           | 2400 – 2420 MHz         | 2,400,000 – 2,420,000 kHz   |
+| 2       | 2430 MHz         | 2,430,000 kHz           | 2420 – 2440 MHz         | 2,420,000 – 2,440,000 kHz   |
+| 3       | 2450 MHz         | 2,450,000 kHz           | 2440 – 2460 MHz         | 2,440,000 – 2,460,000 kHz   |
+| 4       | 2470 MHz         | 2,470,000 kHz           | 2460 – 2480 MHz         | 2,460,000 – 2,480,000 kHz   |
+| 5       | 2483.5 MHz       | 2,483,500 kHz           | 2473.5 – 2483.5 MHz     | 2,473,500 – 2,483,500 kHz   |
+#### Signal 0
+2.431258000 GHz | 2431258.000 kHz
+![signal_0](./images/signals/signal0.png)
+#### Signal 1
+2.447257000 GHz | 2447257.000 kHz
+![signal_1](./images/signals/signal1.png)
+#### Signal 2
+2.450225000 GHz | 2450225.000 kHz
+![signal_2](./images/signals/signal2.png)
+#### Signal 3
+2.471275000 GHz | 2471275.000 kHz
+![signal_2](./images/signals/signal2.png)
+
+#### Signal Summary
+
+
+
+## Run
+`python3 read.py`

read.py

@@ -14,7 +14,7 @@ global MASKS
 global ACCESS
 
 def asb (a):
-    return int(b,16)
+    return int(a,16)
 
 def strobe(command):
     """Send a command strobe to CC2500"""
@@ -42,25 +42,6 @@ def read_register(addr):
     response = spi.xfer2([READ_SINGLE | addr, 0x00])
     return response[1]
 
-def init_cc2500():
-    spi.open(0, 0)  # Bus 0, CE0 (Pin 24)
-    spi.max_speed_hz = 2000000  # Safe start speed
-    spi.mode = 0b00  # SPI mode 0
-
-    print("Sending SRES (reset)...")
-    spi.xfer2([SRES])
-    time.sleep(0.1)
-
-    print("Sending SNOP (no-op)...")
-    status = spi.xfer2([SNOP])[0]
-    print(f"Status byte: 0x{status:02X}")
-
-    print("Reading VERSION register...")
-    version = read_register(0x31)
-    print(f"CC2500 VERSION register: 0x{version:02X}")
-
-    spi.close()
-
 def send_packet(data):
     # Flush TX FIFO
     strobe(0x3B)  # SFTX

srfexp_json.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<registerexporttemplate>
+  <name><![CDATA[JSON]]></name>
+  <commentStart><![CDATA[//]]></commentStart>
+  <commentEnd><![CDATA[]]></commentEnd>
+  <paramSummary><![CDATA[0]]></paramSummary>
+  <paTable><![CDATA[0]]></paTable>
+  <header><![CDATA[{
+]]></header>
+  <registers><![CDATA[    "@RN@"@<<@: @<<@{ "hex":"0x@VH@", "dec":@VD@},]]></registers>
+  <footer><![CDATA[}]]></footer>
+  <filename><![CDATA[@CHIPID@_simple_link_reg_config.json]]></filename>
+  <devices><![CDATA[]]></devices>
+</registerexporttemplate>