From feb1513b4699ea915c0024c0860c019c112c42b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20P=C3=A9rez=20Penichet?= <cperezpenichet@gmail.com>
Date: Wed, 24 Oct 2018 15:26:40 +0200
Subject: [PATCH] Unmodulated carrier transmission for cc2420

Modified the cc2420 driver to enable the radio test
mode to emit unmodulated carriers (tones).
A carrier can be enabled using the normal radio driver
API:
NETSTACK_CONF_RADIO.set_value(
    RADIO_PARAM_POWER_MODE,
    RADIO_POWER_MODE_CARRIER_ON);

Once enabled, the carrier can be disabled like this:
NETSTACK_CONF_RADIO.set_value(
    RADIO_PARAM_POWER_MODE,
    RADIO_POWER_MODE_CARRIER_OFF);
---
 arch/dev/cc2420/cc2420.c | 41 +++++++++++++++++++++++++++++++++++++++-
 os/dev/radio.h           |  4 +++-
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/arch/dev/cc2420/cc2420.c b/arch/dev/cc2420/cc2420.c
index a1572b0ef..7dfa1900b 100644
--- a/arch/dev/cc2420/cc2420.c
+++ b/arch/dev/cc2420/cc2420.c
@@ -114,6 +114,7 @@ PROCESS(cc2420_process, "CC2420 driver");
 #define CORR_THR(n) (((n) & 0x1f) << 6)
 #define FIFOP_THR(n) ((n) & 0x7f)
 #define RXBPF_LOCUR (1 << 13);
+#define TX_MODE (3 << 2)
 
 int cc2420_on(void);
 int cc2420_off(void);
@@ -135,6 +136,8 @@ static void set_poll_mode(uint8_t enable);
 static void set_send_on_cca(uint8_t enable);
 static void set_auto_ack(uint8_t enable);
 
+static void set_test_mode(uint8_t enable, uint8_t modulated);
+
 signed char cc2420_last_rssi;
 uint8_t cc2420_last_correlation;
 
@@ -156,7 +159,11 @@ get_value(radio_param_t param, radio_value_t *value)
   }
   switch(param) {
   case RADIO_PARAM_POWER_MODE:
-    *value = receive_on ? RADIO_POWER_MODE_ON : RADIO_POWER_MODE_OFF;
+    if ((getreg(CC2420_MDMCTRL1) & TX_MODE) & 0x08) {
+      *value = RADIO_POWER_MODE_CARRIER_ON;
+    } else {
+      *value = receive_on ? RADIO_POWER_MODE_ON : RADIO_POWER_MODE_OFF;
+    }
     return RADIO_RESULT_OK;
   case RADIO_PARAM_CHANNEL:
     *value = cc2420_get_channel();
@@ -237,6 +244,11 @@ set_value(radio_param_t param, radio_value_t value)
       cc2420_off();
       return RADIO_RESULT_OK;
     }
+    if(value == RADIO_POWER_MODE_CARRIER_ON ||
+       value == RADIO_POWER_MODE_CARRIER_OFF) {
+      set_test_mode((value == RADIO_POWER_MODE_CARRIER_ON), 0);
+      return RADIO_RESULT_OK;
+    }
     return RADIO_RESULT_INVALID_VALUE;
   case RADIO_PARAM_CHANNEL:
     if(value < 11 || value > 26) {
@@ -1120,3 +1132,30 @@ set_send_on_cca(uint8_t enable)
   send_on_cca = enable;
 }
 /*---------------------------------------------------------------------------*/
+/* Enable or disable radio test mode emmiting modulated or unmodulated 
+ * (carrier) signal. See datasheet page 55.
+*/
+static uint16_t prev_MDMCTRL1, prev_DACTST;
+
+static void
+set_test_mode(uint8_t enable, uint8_t modulated)
+{
+  if (enable) {
+    prev_MDMCTRL1 = getreg(CC2420_MDMCTRL1);
+    setreg(CC2420_MDMCTRL1, 0x050C); 
+    if (!modulated) {
+      prev_DACTST = getreg(CC2420_DACTST);
+      setreg(CC2420_DACTST, 0x1800);
+    }
+    /* actually starts the test mode */    
+    strobe(CC2420_STXON);
+  } else {
+    if (!modulated) {
+      setreg(CC2420_DACTST, prev_DACTST);
+    }
+    setreg(CC2420_MDMCTRL1, prev_MDMCTRL1);
+    /* actually stops the carrier */
+    strobe(CC2420_SRFOFF);
+  }
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/dev/radio.h b/os/dev/radio.h
index e6ca64f3d..e279e9efe 100644
--- a/os/dev/radio.h
+++ b/os/dev/radio.h
@@ -196,7 +196,9 @@ enum {
 /* Radio power modes */
 enum {
   RADIO_POWER_MODE_OFF,
-  RADIO_POWER_MODE_ON
+  RADIO_POWER_MODE_ON,
+  RADIO_POWER_MODE_CARRIER_ON,
+  RADIO_POWER_MODE_CARRIER_OFF
 };
 
 /**