I believe I know what the problem is. The latest i2C packages are broken pyOmegaExpansion_0.5-1_mipsel_24kc.ipk pyOnionI2C_0.5-1_mipsel_24kc.ipk Have the problem I described. I dropped back to pyOmegaExpansion_0.4-1_mipsel_24kc.ipk pyOnionI2C_0.4-1_mipsel_24kc.ipk And the problem went away.