Test Points Can't Forget Those

A project log for SunLeaf

A solar powered wireless picopower sensor module with cloud Datalogging and control geared towards plant and environmental monitoring

AVR (lordKiCAD)AVR (lordKiCAD) 10/04/2016 at 01:360 Comments

So we got another update on the hardware revision today. Two logs back I mentioned that some of the further tweaks to the 0.2a design would be test points. Since the last log I have been working on just that. Test points are very important when designing mixed signal circuit boards with lots of stuff packed on to them. Test points are typically used for debugging problems with the circuit that the designer didn't expect , they are handy for development software debugging, and lastly they are import for confirming desired function of hardware after being assembled in the factory.

The first version of the Sunleaf version 0.1a had test points but not enough of them, there were a few signals here and there that we wanted to be able to probe more easily. Also version 0.1a did not have nearly all the signals for testing complete function since we are looking at mass production we need to have all the important signals available as test points so we can ship working boards. So here is a quick look of the SunLeaf with the newly added test points:

You can see that many test points were crammed onto the PCB without altering its size further. This should make testing and development a lot easier, as we move forward. The signals that now have test points indlude:

- UART_S_TX - UART TX for sensors, runs to the multiplexer/demultiplexer

- UART_S_RX - UART RX for sensors, runs to the multiplexer/demultiplexer

- USW_S1 - UART multiplexer toggle

- USW_EN - UART multiplexer enable

- USW_S0 - UART multiplexer toggle

- BAT_VOLT - Battery voltage sense signal. right off the voltage divider

- I2C_SCL - I2C SCL running from MCU to multiplexer

- I2C_SDA - I2C SDA running from the MCU to multiplexer

- EN1_IMUX - I2C multiplexer toggle 1

- EN3_IMUX - I2C multiplexer toggle 3

- EN2_IMUX - I2C multiplexer toggle 2

- EN4_IMUX - I2C multiplexer toggle 4



- ESP_ST_RST - ESP to STM32 reset toggle

- USB: D+, D-, VBUS - USB signals

- ESP_PGM_MODE - ESP program mode signal coming off the STM32

- ESP_URX - UART RX running to ESP

- ESP_UTX - UART TX Running to ESP

- STM_ESP_RST - STM32 toggle ESP reset

- Solar input

- BAT - battery signal

- THERM - battery thermistor signal

- Power Good on charge controller

- Charge good signal on charge controller

- LDO regulator input and output.

Now there are not test points on 100% of the pins/signals. The sensor connectors have been left out, only because they will either be met with connectors or pogo pins on the factor test jig PCB. So that concludes our test points. Stay tuned as we get closer to the next build!