We have all of our GPIO configured to run at 1.8V, but it looks like the boot ROM has the UARTs configured for 3.3V? When the DA14681 part is reset, and it is looking for sources to boot from, we see 3.3V pulses on the P1.3 UART TX line. (Scope capture attached.) We have devices connected to these pins that are running off of a 1.8V supply, and are not 3.3V tolerant. We are not running the production boot flow yet, as we are still under development. We are booting from a QSPI flash part. Two questions:
Is there a way to fix this now, so that we never see these 3.3V pulses?
When we get to production, will these pulses never happen because we will be booting from QSPI?
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Hi chris.arney,
For this reason the TCS field of the OTP header is available, you can directly set the pad's power source to the particular level by. So in order to set the port pins to be powered from the 1V8 instead of the 3V3 the following registers should be programmed in the OTP header Trim and Calibration Section (TCS):
P0_PADPWR_CTRL_REG (0x500030c0)
P1_PADPWR_CTRL_REG (0x500030c2)
P2_PADPWR_CTRL_REG (0x500030c4)
P3_PADPWR_CTRL_REG (0x500030c6)
P4_PADPWR_CTRL_REG (0x500030c8)
The settings can be programmed either over UART or JTAG using the Smart Snippets or the CLI programmer, i would recommend the cli implementation instead of the Smart Snippets, you will be able to find examples for the cli commands in the UM-B-044 Software Platform Reference.pdf check for the write_tcs command.
生产或开发没关系ttings are applied as soon as the device starts booting before the sequential booting starts. And yes when in production mode the serial booting is canceled, so you wont see the scanning sequence, since you will directly boot from SPI.
Thanks MT_dialog