I’m testing the stability of the Mayfly with the Digi WiFi S6B with software using the 0.27.5 base., running off the LiPo battery.
Some of the the WiFi S6B hybrids initially connect to the WiFi network, get NIST time, and then later after a couple of cycles of sleeping/waking will no longer connect to the wifi. I’ve connected a Salaea Logic Analyzer (8 Channels) to a number of pins on the WiFi S6B, and its showing problems with the power rail. The S6B hybrid has a tight specification for Vcc of 3.14 to 3.46V
With power supplied from the USB +5V rail(500mA)+LiIon, the Salaea Analog channel shows the Vcc at 3.266V, and when sleep req is activated, there is a 20uS glitch to 3.118V.
RF devices require good decoupling, and the LTE adapter has this decoupling. I’ve modified an LTE adapter to take power from the Mayfly Vcc ~ nominally 3.3V – and feed it into the LTE adapter’s power socket. I’ve also added a large capacitor 680uF with Low Series ESR 68mOhms to the 2pin power socket. (Wurth 860080274013)
I expect this to smooth any power surges from the S6B.
With Battery Power LiIon nominally 4.2V, and this carrier board, on power up, after reset there are some extended power spikes of 4mS, that dips from 3.229V to 3.06V.
After running for over 8hours on an speedy soak test cycle of sleeping/waking taking readings and POSTing to MMW every 2minutes successfully – it starts failing to connect to the local WiFi. Its left running for the next 48hours over the weekend, and fails to reconnect.
Just wondering if there are any suggestions?