Power LoRa disco board external

[Jeroen deBuffel]

Posted on July 05, 2017 at 14:32

Have been playing with the B-L072Z-LRWAN1 and it all works fine. Now we would like to hook up directly to the Murata ABZ (via the break out / CN2 and CN3).

As a start I have externally powered the ABZ. I expected the ABZ to send out LoRa messages as it does when connecting the Disco board via USB. However there are no LoRa message getting out. What am I missing here? Suggestions are appreciated

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[Tesla DeLorean]

Posted on July 05, 2017 at 17:14

Where exactly are you inserting power? You'll need a lot more specificity here for me to understand what you're doing or have achieved.

Look at the state of the NRST signal.

For debugging without an debugger, consider outputting telemetry via a USART so you have some means of observation to understand what is happening.

[Jeroen deBuffel]

Posted on July 13, 2017 at 13:37

When connecting via external power supply (battery e.g) the MCU_nRST remains 'low'. After feeding the MCU_nRST with 3.3V the ABZ started and the LoRa messages were sent out. USART I am working on ... thanks Clive!

[Jeroen deBuffel]

Posted on July 05, 2017 at 21:40

Thanks. I did power the ABZ via 2 different manner:

1> 3 batteries -> LED7 turned ON (red)

2> Via VCC_MCU / VDD_RF / and USB VDD pins on CN2 -> LED7 turned ON (red)

Further I did not change anything to the disco board. Tomorrow I will connect the USART and check the NRST (too late now over here)

[Jeroen deBuffel]

Posted on July 13, 2017 at 17:36

External powering is working fine.

What I want to do next is to be able to send commands to the ABZ via USART. Have done the following:

1> Uploaded AT_Slave software (from STM32CubeExpansion sw (v1.1.1) to the disco board

2> Connected another board (acting as 'AT master') directly to the LRWAN disco board.

      Using USART1_RX (PA10) and USART1_TX (PA9)

3> Send AT commands to the LRWAN1 disco board (9600, 8bits, no parity, 1 stopbit)

I see no serial response coming from the LRWAN board. So I am wondering if my setup is correct?

[Tesla DeLorean]

Posted on July 13, 2017 at 17:53

You'd have to modify the firmware. The build as provided uses LPUART1 on PA2/PA3 (ie VCP/SHIELD connection)

[Jeroen deBuffel]

Posted on July 13, 2017 at 19:44

Guess you are familiar with these boards :) 

Made some changes In \LoRa\AT_Slave\inc\mlm32l0xx_hw_conf.h (see below). Will continue to test tonight. So far no feedback on AT commands ...

// Jeroen 13-7-2017

♯ define UARTX_TX_PIN                    GPIO_PIN_9

♯ define UARTX_TX_GPIO_PORT    GPIOA

♯ define UARTX_TX_AF                     GPIO_AF4_USART1

♯ define UARTX_RX_PIN                    GPIO_PIN_10

♯ define UARTX_RX_GPIO_PORT    GPIOA

♯ define UARTX_RX_AF                     GPIO_AF4_USART1

// Original code

// ♯ define UARTX_TX_PIN                    GPIO_PIN_2

// ♯ define UARTX_TX_GPIO_PORT    GPIOA

// ♯ define UARTX_TX_AF                     GPIO_AF6_LPUART1

// ♯ define UARTX_RX_PIN                    GPIO_PIN_3

// ♯ define UARTX_RX_GPIO_PORT    GPIOA

// ♯ define UARTX_RX_AF                     GPIO_AF6_LPUART1

//

In the end I might want to use another MCU to control the ST ABZ LoRa board. So trying to get this working ...