dbsrx: modification docs

1 files changed, 42 insertions, 1 deletions

diff --git a/host/docs/dboards.rst b/host/docs/dboards.rst
index 8e6ecc4ae..b66fd2069 100644
--- a/host/docs/dboards.rst
+++ b/host/docs/dboards.rst
@@ -32,7 +32,7 @@ The Basic TX and LFTX boards have 1 quadrature subdevice using both antennas.
 
 The boards have no tunable elements or programmable gains.
 Though the magic of aliasing, you can up-convert signals
-greater than the nyquist rate of the DAC.
+greater than the Nyquist rate of the DAC.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 DBSRX
@@ -100,3 +100,44 @@ the receive antenna will always be set to RX2, regardless of the settings.
 Transmit Gains: **PGA0**, Range: 0-25dB
 
 Recieve Gains: **PGA0**, Range: 0-31.5dB
+
+------------------------------------------------------------------------
+Daughterboard Modifications
+------------------------------------------------------------------------
+
+Sometimes, daughterboards will require modification
+to work on certain frequencies or to work with certain hardware.
+Modification usually involves moving/removing a SMT component
+and burning a new daughterboard id into the eeprom.
+
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+DBSRX
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Due to different clocking capabilities,
+the DBSRX will require modifications to operate on a non-USRP1 motherboard.
+On a USRP1 motherboard, a divided clock is provided from an FPGA pin
+because the standard daughterboard clock lines cannot provided a divided clock.
+However, on other USRP motherboards, the divided clock is provided
+over the standard daughterboard clock lines.
+
+**Step 1: Move the clock configuration resistor**
+
+Remove R193 (which is 10 ohms, 0603 size) and put it on R194, which is empty.
+This is made somewhat more complicated by the fact that the silkscreen is not clear in that area.
+R193 is on the back, immediately below the large beige connector, J2.
+R194 is just below, and to the left of R193.
+The silkscreen for R193 is ok, but for R194,
+it is upside down, and partially cut off.
+If you lose R193, you can use anything from 0 to 10 ohms there.
+
+**Step 2: Burn a new daughterboard id into the EEPROM**
+
+With the daughterboard plugged-in, run the following commands:
+::
+
+    cd <prefix>/share/uhd/utils
+    ./usrp_burn_db_eeprom --id=0x000d --unit=RX --args=<args> --db=<db>
+
+* <args> are device address arguments (optional if only one USRP is on your machine)
+* <db> is the name of the daughterboard slot (optional if the USRP has only one slot)