Spresense can reset the system in the following way.
Press SW1 on the main board.
UART connection (DTR signal trigger) by serial monitor etc.
Reduce the signal level of JP3’s 3rd pin of the extension board to Low (see details below)
When a system reset is applied, from the CXD5247 of the LSI that manages the power supply and each power supply LSI
Since power supply stops for a moment, caution is required when connecting an external circuit to an extension board or Add-on board.
Resetting pin No.3 of JP3 on the extension board can be used as bidirectional. That is
Input the signal to reset the system from the extension board.
Reset the system connected outside the extension board.
Although it can be used as any of the above, please connect the recommended circuit shown below as an external circuit. However, as a user device to be connected, a microprocessor LSI
We assume high impedance devices such as.
Also, the reset signal (XRST_PIN_1.8V) on pin No.1 of JP2 on the main board outputs the system reset status. It is Low when the system reset is applied, and in other states
It outputs High (1.8V). By using this signal, it is possible to reset the Add-on board etc at the same timing as the sensing processor CXD5602.
The maximum current that can be drained from the Spresense main board micro USB connector is 500mA.
This is true also when both the main board and extension board are mounted and have separate USB power connected.
The 500mA current that is sourced by the main board will be shared with the Add-on board too.
In case that the 500mA current from the micro USB connector is not sufficient it is possible to supply more power using the battery terminal CN1 on the main board.
The CN1 battery connector’s recommended operating voltage is 3.6 to 4.4V with an absolute maximum voltage of 7V.
Using the CN1 battery connector the sourced current from EXT_VDD (JP2 pin number 3) to an Add-on board can be increased.
See the table below for recommended battery connector that will fit CN1.
It is necessary to solder on the main board to mount a battery connector on CN1.
Modifying the Spresense boards will void the warranty. Please do it at your own risk.
表格 1. List of battery connector that will fit on CN1 of the main board:
Japan Crimp Terminal Mfg. Co., Ltd.
PH male connector
PH female connector
图表 1. Powering the main board from the battery connector CN1.
Powering the main board via the CN1 battery connector will boot the Spresense system even if the micro USB is not connected.
Even if power is supplied from PH connector (CN1) on the main board, you can supply power from the microUSB connector on the main board and extension board.
The lower limit of the voltage output of the EXT_VDD pin is about 4V.