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diff --git a/host/docs/usrp1.rst b/host/docs/usrp1.rst new file mode 100644 index 000000000..8b274a2b3 --- /dev/null +++ b/host/docs/usrp1.rst @@ -0,0 +1,86 @@ +======================================================================== +UHD - USRP1 Application Notes +======================================================================== + +.. contents:: Table of Contents + +------------------------------------------------------------------------ +Specify a non-standard image +------------------------------------------------------------------------ +The standard USRP1 images installer comes with two FPGA images: + * **usrp1_fpga.rbf:** 2 DDCs + 2 DUCs + * **usrp1_fpga_4rx.rbf:** 4 DDCs + 0 DUCs + +By default, the USRP1 uses the FPGA image with 2 DDCs and 2 DUCs. +However, a device address parameter can be used to override +the FPGA image selection to use an alternate or a custom FPGA image. +See the images application notes for installing custom images. + +Example device address string representations to specify non-standard firmware and/or FPGA images: + +:: + + fpga=usrp1_fpga_4rx.rbf + + -- OR -- + + fw=usrp1_fw_custom.ihx + + -- OR -- + + fpga=usrp1_fpga_4rx.rbf, fw=usrp1_fw_custom.ihx + +------------------------------------------------------------------------ +Missing and emulated features +------------------------------------------------------------------------ +The USRP1 FPGA does not have the necessary space to support the advanced +streaming capabilities that are possible with the newer USRP devices. +Some of these features are emulated in software to support the API. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +List of emulated features +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +* Setting the current device time +* Getting the current device time +* Transmitting at a specific time +* Transmitting a specific number of samples +* Receiving at a specific time +* Receiving a specific number of samples +* End of burst flags for transmit/receive +* Notification on late stream command +* Notification on late transmit packet +* Notification on underflow or overflow +* Notification on broken chain error + +**Note:** +These emulated features rely on the host system's clock for timed operations, +and therefore may not have sufficient precision for the application. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +List of missing features +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +* Start of burst flags for transmit/receive + +------------------------------------------------------------------------ +Hardware setup notes +------------------------------------------------------------------------ + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +External clock modification +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +The USRP can be modified to accept an external clock reference instead of the 64MHz onboard reference. + * Solder SMA (LTI-SASF54GT) connector to J2001 + * Move 0 ohm 0603 resistor R2029 to R2030 + * Move 0.01uF 0603 capacitor C925 to C926 + * Remove 0.01uF 0603 capacitor C924 + +The new external clock needs to be a square wave between +7dBm and +15dBm + +After the hardware modification, +the user should burn the setting into the EEPROM, +so UHD can initialize with the correct clock rate. +Run the following commands to record the setting into the EEPROM: +:: + + cd <install-path>/share/uhd/utils + ./usrp_burn_mb_eeprom --args=<optional device args> --key=mcr --val=<rate> |