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| author | Lars Amsel <lars.amsel@ni.com> | 2021-10-01 14:59:26 +0200 |
|---|---|---|
| committer | Aaron Rossetto <aaron.rossetto@ni.com> | 2022-01-10 14:55:44 -0600 |
| commit | 0e7553cd1a8758a8488afc2efaff7295b351e7fe (patch) | |
| tree | f4ca9535e68f520da4baa730482b5cda1138afb2 /mpm/python | |
| parent | 4725e97c6d6baa82d414ea89623ca32732d9bea1 (diff) | |
| download | uhd-0e7553cd1a8758a8488afc2efaff7295b351e7fe.tar.gz uhd-0e7553cd1a8758a8488afc2efaff7295b351e7fe.tar.bz2 uhd-0e7553cd1a8758a8488afc2efaff7295b351e7fe.zip | |
MPM: X410: Set correct tuning word
The comment behind the tuning word is correct but 0x200 does not
give a voltage of 1.65V but 2.5V, because the full range of the
DAC is 5V not 3.3V).
Diffstat (limited to 'mpm/python')
| -rw-r--r-- | mpm/python/usrp_mpm/periph_manager/x4xx_clk_aux.py | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/mpm/python/usrp_mpm/periph_manager/x4xx_clk_aux.py b/mpm/python/usrp_mpm/periph_manager/x4xx_clk_aux.py index fcd655d9d..f8dc83a06 100644 --- a/mpm/python/usrp_mpm/periph_manager/x4xx_clk_aux.py +++ b/mpm/python/usrp_mpm/periph_manager/x4xx_clk_aux.py @@ -17,7 +17,13 @@ from usrp_mpm.sys_utils.udev import get_eeprom_paths_by_symbol from usrp_mpm.sys_utils import i2c_dev from usrp_mpm.chips import LMK05318 -X400_CLKAUX_DEFAULT_TUNING_WORD = 0x200 # 1.65V which would be a DAC value of 512 +# DAC AD5338R provides V_out = V_ref * gain (tune_word / 2^N) +# We have gain pin enabled (2) and N = 10 for the AD5338 models +# to provide 1.65V to the OCXO we need: +# tune_word = 1.65V / (2.5V * 2) * 2^10 +# Note: V_vdd = 3.3V so V_out will saturate at 3.3V (it won't reach 5V) +# the tuning word is therefore limited to 0x2A4 +X400_CLKAUX_DEFAULT_TUNING_WORD = 0x152 X400_CLKAUX_DEFAULT_REVISION = 0x1 X400_CLKAUX_I2C_LABEL = 'clkaux_i2c' X400_CLKAUX_SPI_LABEL = 'clkaux_spi' |