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Replace 1.8V LDO U5 with 1.2V MCP1824T-1202E
voltages XP hashboard are 0.8V and 1.2V, not 0.8V and 1.8V like on the ultra
developeralgo222 — Today at 10:26 AM
Tested today. if you are using the original ultra dev board without any changes we have now tested that if U5 @ 1.8V LDO <===> J-Connector (1V8) <==> UART Serial ( Input 1.8V or 1.2V both work and able to communicate to the BM1366 AG/AL chip )
But if you have it same way as in S19 XP Hashboards where its supposed to be 1.2V it does NOT work in current Ultra Dev board i.e if U5 @ 1.2V LDO <===> J-Connector (1V8) <==> UART Serial ( Input 1.2V Does NOT work and will not communicate to the BM1366 AG/AL chip )
For those who planned to switch U5 to 1.2V please hold off until we can figure out why it does not work with 1.2V LDO @ U5
Hold off for now
the minimum supply voltage for the crystal oscillator we are using is 1.8V. if we switch to 1.2V we need to sort this out.
1.2v LDO: TLV70212QBVRQ1 1.2v crystal oscillator: SX3M25.000E20F30THN Test OK
and if at the input of pin 14 you place a voltage divider with two resistors in series, 1k and 2k to ground, the result will be 1.2v at the input of the BM1366... the other line would have a voltage of 1.8v and at pin 14 would have 1.2v. It's just an idea.
Tested with a 1.2V LDO and 1.2v oscillator, it did not work. https://www.digikey.com/en/products/detail/onsemi/NCP114ASN120T1G/6560601 https://www.lcsc.com/product-detail/Oscillators_Shenzhen-SCTF-Elec-SX3M25-000E20F30THN_C5137262.html
Tested with a 1.2V LDO and 1.2v oscillator, it did not work. https://www.digikey.com/en/products/detail/onsemi/NCP114ASN120T1G/6560601 https://www.lcsc.com/product-detail/Oscillators_Shenzhen-SCTF-Elec-SX3M25-000E20F30THN_C5137262.html
I have built several bitaxes with 1.2V LDO and oscillator, and all of them works well.
Is it the oscillator or the ASIC that is not working correctly?
I'll try this out with some LCSC drop-in 1.2V oscillators. if it works I'd like to include in 402
Switched my v400 to the MCP1824T-1202E 1.2V LDO and C5137262 1.2V 25MHz Oscillator. seems to be working -- I'll keep an eye on it.