Mini Mainboard: Difference between revisions

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As opposed to earlier mainboards the current sensor inputs are now designed for 5V input, i.e. 2.5V @ 0A. This interfaces directly with most current sensors that OEMs use and also with Melexis chips, LEM HTFS and Tamura L06P current sensors.
As opposed to earlier mainboards the current sensor inputs are now designed for 5V input, i.e. 2.5V @ 0A. This interfaces directly with most current sensors that OEMs use and also with Melexis chips, LEM HTFS and Tamura L06P current sensors.


=== Hardware detection ===
Because the mini mainboard is primarily meant to be mounted on some sort of base board, we wanted to introduce a detection mechanism for the base board in case any special treatment is needed.
We chose to assign a secondary meaning to the OUT_BRAKE pin because its level can be measured by the ADC. So OUT_BRAKE can be brought to a certain voltage level with a high impedance voltage divider. The voltage level encodes the hardware variant. It will not disturb normal operation because its total resistance is chosen at least one order of magnitude larger than the output impedance of OUT_BRAKE, which is about 270 Ohms.
A the upper voltage divider resistor R1 is connected to the "5V" rail which actually sits at 5.3V. R2 is connected to GND
{| class="wikitable"
|+
!Variant
!R1
!R2
!voltage
!ADC
|-
| -
|47k
|2k7
|0.29 V
|357
|-
| -
|47k
|3k3
|0.35 V
|431
|-
| -
|47k
|3k9
|0.41 V
|504
|-
|Nissan Leaf Gen3
|47k
|4k7
|0.48 V
|598
|-
| -
|47k
|5k1
|0.52 V
|643
|-
| -
|47k
|5k6
|0.56 V
|700
|-
| -
|47k
|6k8
|0.67 V
|831
|-
| -
|47k
|7k5
|0.73 V
|905
|-
| -
|47k
|8k2
|0.79 V
|977
|-
| -
|47k
|9k1
|0.86 V
|1067
|-
| -
|47k
|10k
|0.93 V
|1154
|}
[[Category:OpenInverter]] [[Category:Inverter]]
[[Category:OpenInverter]] [[Category:Inverter]]

Revision as of 20:32, 5 October 2023

Mini mainboard front

The mini mainboard is the smallest form factor openinverter motor control board. It has the same functionality as the Main Board Version 3 but offloads a few components. It is meant to be used as a daughter board on top of an adapter board. The adapter board must (or may) implement:

  • The Wifi module socket
  • Relay drivers

In addition the mini mainboard allows talking to SPI peripherals. Therefore some pins have double mapping:

  • SIG_CRUISE: MOSI (SJ3 must be closed to the right side for that).
  • OUT_BRAKE: MISO
  • OUT_ERR: SCK
  • OUT_OUVTG: /CS

Like previous boards it contains a 5V switching regulator that can be loaded with about 500 mA. Alternatively It can be powered with a single 5V rail, which has to sit at 5.3V though for sufficient resolver excitation amplitude.

As opposed to earlier mainboards the current sensor inputs are now designed for 5V input, i.e. 2.5V @ 0A. This interfaces directly with most current sensors that OEMs use and also with Melexis chips, LEM HTFS and Tamura L06P current sensors.

Hardware detection

Because the mini mainboard is primarily meant to be mounted on some sort of base board, we wanted to introduce a detection mechanism for the base board in case any special treatment is needed.

We chose to assign a secondary meaning to the OUT_BRAKE pin because its level can be measured by the ADC. So OUT_BRAKE can be brought to a certain voltage level with a high impedance voltage divider. The voltage level encodes the hardware variant. It will not disturb normal operation because its total resistance is chosen at least one order of magnitude larger than the output impedance of OUT_BRAKE, which is about 270 Ohms.

A the upper voltage divider resistor R1 is connected to the "5V" rail which actually sits at 5.3V. R2 is connected to GND

Variant R1 R2 voltage ADC
- 47k 2k7 0.29 V 357
- 47k 3k3 0.35 V 431
- 47k 3k9 0.41 V 504
Nissan Leaf Gen3 47k 4k7 0.48 V 598
- 47k 5k1 0.52 V 643
- 47k 5k6 0.56 V 700
- 47k 6k8 0.67 V 831
- 47k 7k5 0.73 V 905
- 47k 8k2 0.79 V 977
- 47k 9k1 0.86 V 1067
- 47k 10k 0.93 V 1154
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