Folks, I've released a new design, Orone-mini-S8J at github.
It is significantly improved over the earlier Orone-mini-S8H.
Several people who built the earlier Orone-mini designs fed back on their experiences. All identified the difficulty of assembling the board using the small NUF2042XV6 USB EMI/ESD. So I have adopted the much larger STF202-22. It is the same part as used on Siy's designs. However, that circuit leaves the USB +5 power line (Vusb) unprotected. So Orone-mini-S8J has a separate discrete Transient Voltage Suppression (TVS) diode protecting the Vusb connection.
Ventosus ran some tests to measure the ADC noise performance of Orone-mini vs Maple. The test results indicated Orone-mini was worse than Maple analogue-power, but better than Maple digital power. As that generation of Orone-mini only connected the digital power supply to av+, and is only a two layer PCB, it was very encouraging.
I've changed the design, so that Orone-mini-S8J now provides av+ from its analogue-power supply.
Note: the analogue supply is only useful to provide external power from av+ when Orone-mini is connected to, about, 9V or less. Several Maple-mini's had suffered voltage regulator failure, which was the reason the earlier Orone-mini's had av+ connected to Orone-mini's higher capacity digital power supply. Just like Maple mini, the small analogue-PSU voltage regulator used for the analogue power supply is limited by its power dissipation. This should not effect Orone-mini when it's run from 5V, by powering it over USB
The board has been extensively reworked to improve the integrity of the ground plane and power distribution (i.e. fewer big holes :-).
Note:These changes necessitated changes to the pin-out of the extra signals and voltages that Orone-mini provides, but which are not available on Maple-mini. Hence Orone-mini-S8J is not pin identical to Orone-mini-S8H. However Orone-mini-S8J is pin identical to Maple-mini.
The silk screen has been slightly updated to highlight the Serial Wire Debug (SWD) pins, making it easier to use with a JTAG-SWD debugger, for example an ST-Link/V2 or the even lower cost ST-Link/V2 on STM32FxDiscovery boards (under $10). These debuggers support hardware break-points, data watch points, single-stepping, etc. using gdb.
Orone-mini is fully pin-compatible, and software compatible with Maple-mini if you assemble it with an STM32F103CB.
Orone-mini can also be assembled using an STM32F303CC, doubling its Flash, and more than doubling SRAM, It could be used with Ventosus' initiated libmaple port for STM32F303. This would have similar performance to an Arduino Due for a similar cost to an eBay clone of an Arduino UNO.
An STM32F303Cx has more, and better peripherals than an STM32F103CB.
For example:
- 4 ADCs vs 2 ADCs, and ADC's are 5msps vs 1Msps (potentially 20Msps vs 2Msps)
- Dual DAC vs none
- 3 SPI vs 2
- 2 advanced timers vs 1 (useful for e.g. brushless motor control)
- 2 I2S vs none
- 17 channel capacitive touch sensing vs none
- 7 analogue comparators vs none
- 4 programmable gain op amps vs none
etc.
AFAIK, an STM32F303 has some much better peripherals than an Arduino Due's SAM3X8E, for example better ADC and analogue signal processing. Further, STM2F303 has 5V tolerant pins, though Due's SAM3X8E has more I/O.
Orone-mini-S8J retains Orone-mini's benefits, described at github.
Summary of changes:
- Larger, easier to assemble USB circuit, without sacrificing any ESD protection
- av+ from analogue power supply (aim is less electrical noise, and better ADC)
- reworked ground plane and crystal oscillator for better ground and lower noise
This is an initial release; I have not yet updated the Bill of Materials. Please feedback any comments on this thread.
Please do not use the design yet. It is not adequately quality assured.
(Full disclosure: I am not a member of LeafLabs staff.)
