From 63f298d020069aab725e688fc929adee6d0b7851 Mon Sep 17 00:00:00 2001
From: Stephen D <webmaster@scd31.com>
Date: Wed, 29 Nov 2023 17:51:57 -0400
Subject: [PATCH] add random delays before txing
---
Cargo.lock | 12 +++++++++-
Cargo.toml | 3 ++-
src/main.rs | 8 +++----
src/radio.rs | 64 +++++++++++++++++++++++++++++++++++++++++++++++-----
4 files changed, 75 insertions(+), 12 deletions(-)
diff --git a/Cargo.lock b/Cargo.lock
index cd0b5a9..d39bb5e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -84,6 +84,7 @@ dependencies = [
"nmea",
"num-traits",
"panic-semihosting",
+ "rand",
"rf4463",
"stm32f4xx-hal",
"systick-monotonic",
@@ -306,7 +307,7 @@ dependencies = [
[[package]]
name = "ham-cats"
version = "0.1.0"
-source = "git+https://gitlab.scd31.com/cats/ham-cats/#81e90ddc21a4aa0e56acd05a18edb658593cf434"
+source = "git+https://gitlab.scd31.com/cats/ham-cats#81e90ddc21a4aa0e56acd05a18edb658593cf434"
dependencies = [
"arrayvec",
"bitvec",
@@ -515,6 +516,15 @@ version = "0.7.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09"
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "rand_core",
+]
+
[[package]]
name = "rand_core"
version = "0.6.4"
diff --git a/Cargo.toml b/Cargo.toml
index a888f86..fd23dba 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,7 +21,7 @@ panic-semihosting = "0.6"
rf4463 = { git = "https://gitlab.scd31.com/stephen/rf4463-lib" }
#rf4463 = { path = "../../rf4463" }
systick-monotonic = "1.0.1"
-ham-cats = { git = "https://gitlab.scd31.com/cats/ham-cats/" }
+ham-cats = { git = "https://gitlab.scd31.com/cats/ham-cats" }
half = { version = "2.3.1", default-features = false }
# TODO can get rid of some of these features
nmea = { version = "0.6.0", default-features = false, features = ["VTG", "GGA", "RMC", "GNS", "GLL"] }
@@ -32,4 +32,5 @@ usb-device = "0.2.9"
crc = "3.0.1"
embedded-storage = "0.2.0"
num-traits = { version = "0.2.17", default-features = false, features = ["libm"] }
+rand = { version = "0.8", default_features = false, features = ["small_rng"] }
# TODO need to add panic-reset at some point
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 626bfe5..661aa2f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,6 +13,7 @@ mod status;
mod voltage;
pub const MAX_PACKET_LEN: usize = 8191;
+pub const SYS_TICK_FREQ: u32 = 1000;
#[rtic::app(device = stm32f4xx_hal::pac, peripherals = true, dispatchers = [USART6])]
mod app {
@@ -45,7 +46,7 @@ mod app {
shell::Shell,
status::Status,
voltage::VoltMeter,
- MAX_PACKET_LEN,
+ MAX_PACKET_LEN, SYS_TICK_FREQ,
};
const SYS_CLK: u32 = 84_000_000;
@@ -59,7 +60,7 @@ mod app {
};
#[monotonic(binds = SysTick, default = true)]
- type MyMono = Systick<10_000>;
+ type MyMono = Systick<{ SYS_TICK_FREQ }>;
#[local]
struct Local {
@@ -117,7 +118,6 @@ mod app {
green.set_low();
// setup volt meter
-
let volt_pin = gpioc.pc0.into_analog();
let volt_adc = Adc::adc1(dp.ADC1, true, AdcConfig::default());
let volt_meter = VoltMeter::new(volt_pin, volt_adc);
@@ -145,7 +145,7 @@ mod app {
let spi = Spi::new(dp.SPI1, (sclk, miso, mosi), MODE, 10.MHz(), &clocks);
let buf = singleton!(: [u8; MAX_PACKET_LEN] = [0; MAX_PACKET_LEN]).unwrap();
- let radio = RadioManager::new(spi, sdn, cs, delay, buf, config.enable_digipeating);
+ let radio = RadioManager::new(spi, sdn, cs, delay, buf, &config);
radio
};
diff --git a/src/radio.rs b/src/radio.rs
index fcc6692..69af6e4 100644
--- a/src/radio.rs
+++ b/src/radio.rs
@@ -1,4 +1,5 @@
use ham_cats::{buffer::Buffer, packet::Packet};
+use rand::{rngs::SmallRng, Rng, SeedableRng};
use rf4463::{config::RADIO_CONFIG_CATS, error::TransferError, Rf4463};
use rtic::Mutex;
use stm32f4xx_hal::{
@@ -8,8 +9,9 @@ use stm32f4xx_hal::{
spi::{self, Spi},
timer::Delay,
};
+use systick_monotonic::fugit::Duration;
-use crate::MAX_PACKET_LEN;
+use crate::{app::monotonics::MyMono::now, config::Config, MAX_PACKET_LEN, SYS_TICK_FREQ};
type SdnPin = gpio::Pin<'B', 12, gpio::Output>;
type CsPin = gpio::Pin<'A', 8, gpio::Output>;
@@ -20,6 +22,7 @@ pub struct RadioManager<'a> {
radio: Radio,
buf: &'a mut [u8; MAX_PACKET_LEN],
enable_digipeating: bool,
+ rng: SmallRng,
}
impl<'a> RadioManager<'a> {
@@ -29,7 +32,7 @@ impl<'a> RadioManager<'a> {
cs: CsPin,
delay: MyDelay,
buf: &'a mut [u8; MAX_PACKET_LEN],
- enable_digipeating: bool,
+ config: &Config,
) -> Option<Self> {
let mut radio = Rf4463::new(spi, sdn, cs, delay, &mut RADIO_CONFIG_CATS.clone()).ok()?;
@@ -38,10 +41,15 @@ impl<'a> RadioManager<'a> {
radio.start_rx(None, false).ok()?;
+ let enable_digipeating = config.enable_digipeating;
+ let seed = rand_seed_from_str(&config.callsign) ^ u64::from(config.ssid);
+ let rng = SmallRng::seed_from_u64(seed);
+
Some(Self {
radio,
buf,
enable_digipeating,
+ rng,
})
}
@@ -92,10 +100,10 @@ impl<'a> RadioManager<'a> {
data: &[u8],
ident: Option<(&str, u8)>,
) -> Option<()> {
- // don't want to transmit on top of a packet
- while self.radio.is_busy_rxing().ok()? {
- self.tick(led, ident).ok()?;
- }
+ // ensures we don't tx over a packet,
+ // and adds some random delay so that every node
+ // if offset slightly
+ self.tx_delay(led, ident)?;
led.lock(|l| l.set_high().ok());
self.radio.start_tx(data).ok()?;
@@ -108,6 +116,37 @@ impl<'a> RadioManager<'a> {
Some(())
}
+ fn tx_delay<P: OutputPin, M: Mutex<T = P>>(
+ &mut self,
+ led: &mut M,
+ ident: Option<(&str, u8)>,
+ ) -> Option<()> {
+ loop {
+ let delay_ms = self.rng.gen_range(0..50);
+
+ let mut rx = false;
+ let thres = now() + Duration::<u64, 1, { SYS_TICK_FREQ }>::millis(delay_ms);
+ while now() < thres {
+ self.tick(led, ident).ok()?;
+
+ while self.radio.is_busy_rxing().ok()? {
+ rx = true;
+ self.tick(led, ident).ok()?;
+ }
+
+ if rx {
+ // if we rx'd a packet, we need to draw a new random time and start again
+ break;
+ }
+ }
+
+ if !rx {
+ // didn't an rx packet, so we're safe to leave
+ break Some(());
+ }
+ }
+ }
+
fn handle_packet_rx<P: OutputPin, M: Mutex<T = P>>(
&mut self,
led: &mut M,
@@ -128,3 +167,16 @@ impl<'a> RadioManager<'a> {
}
}
}
+
+fn rand_seed_from_str(s: &str) -> u64 {
+ let mut out = 0;
+
+ for (i, &b) in s.as_bytes().iter().enumerate() {
+ let i = i % 4;
+ let b: u64 = b.into();
+
+ out ^= b << (i * 8);
+ }
+
+ out
+}
--
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