Errata and revision differences

Revision overview

Revision	Changes
V1.5	Adds a dedicated PSRAM LDO rail, which makes the 32 MiB PSRAM configuration possible; this revision targets the 32 MiB build; the microSD card-detect pull-down R11 changed from 10 kΩ to 1 kΩ (PF6).
V1.4	Corrects the PD pin silkscreen numbering, see the V1.3 errata below. When using only the 16 MiB configuration, changing R11 to 1 kΩ on V1.4 is enough.
V1.3	Initial release.

Caution

Which revision do I need? If you only need the F101S3 + 16 MiB PSRAM, V1.4 is enough: change R11 to 1 kΩ and the microSD detect problem is gone. V1.5 exists specifically for the 32 MiB PSRAM configuration, which needs the additional PSRAM LDO rail.

V1.3: PD silkscreen numbering error

F101S3 has no PD10 and PD11. The V1.3 PCB kept numbering consecutively after PD9, which makes every PD silkscreen label from PD10 onwards two lower than the real SoC GPIO number. This is an identification error in the V1.3 silkscreen, and V1.4 corrects it. When doing pinmux, writing software or reading the schematic, use the “Actual SoC GPIO / V1.4 silkscreen” column in the table below.

V1.3 silkscreen	Actual SoC GPIO / V1.4 silkscreen	Effect
PD10	PD12	MUX selection must use PD12
PD11	PD13	MUX selection must use PD13
PD12–PD20	PD14–PD22	Each corresponding label is offset by +2

Pay particular attention to this on V1.3 boards when configuring functions that pass through these pins, such as display, LVDS/DSI and UART2/4/5. The full mapping table is in Pinout.

V1.4 and earlier: microSD card-detect (CD) pull-down too large

The microSD card-detect signal is PF6, pulled down by R11. On V1.4 and earlier boards R11 is 10 kΩ, which is too high for the pin to settle reliably below the logic-low threshold, so card insertion may not be detected.

• Software workaround: set PF6’s output drive strength to its lowest setting in pinctrl.
• Hardware fix: change R11 to 1 kΩ (V1.5 already does this).

Look here first when something goes wrong

Symptom	Possible cause
On V1.3, nothing happens after configuring PD12–PD20	Silkscreen offset; you should actually use PD14–PD22
The microSD card is inserted but the system does not see it	PF6 card-detect problem; handle it as described above
Want 32 MiB PSRAM but it is unstable	Needs the V1.5 PSRAM LDO; V1.4 and earlier will not work