Can PIC18F2550 work at 3V ?

[milan.rajik]

Can PIC18F2550 work at 3V ?

In PIC18F2550 datasheet it is mentioned that it works from 200 to 5.5V. So, Can I power the chip using a 3V CR2032 button cell with crystal of 4 MHz ? I need to connect a mikroe SpeakUp and Xbee which work at 2.8 - 3.4V to PIC18F2550. The only components in the circuit will be a CR2032 with a sliding switch to power the circuit, an Xbee Pro, a mikroe SpeakUp and PIC18F2550 running at 4 MHz.

 

[wp100]

Hi,

The opening page of the Datasheets are misleading, they refer to the entire range of that particular family including the LF versions.

If you look in the Electrical Characteristics figs 28.1 and 28. 2 they clearly show the voltage / crystal ranges of the standard and LF versions.

 

[milan.rajik]

Ok. It shows that I can't use PIC18F device. I will better use PIC32MX150F128B which can work at 3V. Will it work, the PIC32MX + SpeakUp + XBee Pro powered by a CR2032 3V cell ? Xbee will be configured for low power for a distance of 50 meters.

 

[wp100]

Hi

Again a quick look at the datasheets should tell you.

A Cr2032 cells is good for 3v 210 maH

A Xbee pro - see the picture

A Pic32 typically according to the datasheet , typically 10ma dependent on crystal frequency.

Speakup - cannot see a datasheet but again I would allow 10ma.

How long would all that run for on a single cell ? - don't thing very long when sending or receiving with the Xbee .. unless you parallel a lot of cells..

 

[milan.rajik]

I will have a SPDT sliding switch. Only when I need to control any device I will turn ON the switch which will power PIC32+SpeakUp+XBee and after speaking into speakup and device operated I will turn OFF the power.

 

[bigdogguru]

I will have a SPDT sliding switch. Only when I need to control any device I will turn ON the switch which will power PIC32+SpeakUp+XBee and after speaking into speakup and device operated I will turn OFF the power.

Why not have the PIC32 power down the XBee and, if available, put the SpeakUp in low power mode along with itself.

Can you provide a link to the SpeakUp datasheet or possibly upload it? As wp100 mentioned it seems to be difficult to find.

The SpeakUp maybe able to trigger the awakening of the PIC32 which in turn should be able to power up the XBee.

In any event, power consumption will be drastically cut if the PIC32 is in a low power or sleep mode and the XBee powered down.



BigDog

 

[milan.rajik]

This page contains the SpeakUp manual.

https://www.mikroe.com/click/speakup/


I will try that.

 

[bigdogguru]

The PIC32 may not be the best choice for the application, there are numerous PIC18Fs which can function properly at 3V.

The prudent choice for the microcontroller depends largely on the tasks assigned to the device.

In any event, properly utilizing a device's low power or sleep modes is imperative for efficient battery powered operation.

BigDog

- - - Updated - - -

After reviewing the SpeakUp documentation, I not sure there is any requirement for an additional microcontroller like the PIC32 or PIC18.

The board offers a STM32F4 series microcontroller which may more than suffice for many applications.

BigDog

 

[milan.rajik]

The PIC32 may not be the best choice for the application, there are numerous PIC18Fs which can function properly at 3V

I really don't want to use a MCU for this but doesn't know whether just SpeakUP+XBee+CR2032 work or not. I have another thread regarding this. I have given order for a prototype board (PCBs). Will get it in a week. In that I have used a CR2032 with a SPDT switch to save battery. The battery powers Xbee and SpeakUp at 3V. According to mikroe the speakup sends out index of matched voice message (int values) like 0, 1, 2, 3,....200...

I don't know whether just connecting Tx of SpeakUp to Rx of Xbee and powering both will make Xbee transmit the data 0,1,2,3,.... to receiver Xbee. If it works then I will eliminate the PIC18F or PIC32.


I did a test using Nano. I put a Nano and XBee into ITEAD Nano shield and uloaded a sketch which sends out 0,1,2,3,..... through UART Tx and hence Xbee transmitter. I connected another Xbee to PC USB port and saw that the data sent from Nano board's Xbee is received by receiver Xbee. I am waiting for Proto board.

I am attaching rough image of the remote control board in which Tx of SpeakUp will be connected to Rx of XBee and 3.3V and GND pins of SpeakUp and XBee will be connected to CR2032. I hope it works without the need of a MCU. All I want to transmit is the matched voice message index sent out by SpeakUp through its UART Tx.

After reviewing the SpeakUp documentation, I not sure there is any requirement for an additional microcontroller like the PIC32 or PIC18.

mikroe did not give a clear answer to my question asked here.

https://www.mikroe.com/forum/viewtopic.php?f=147&t=60417

 

[bigdogguru]

When utilizing XBees in the simplest method, they are essentially forming a virtual serial cable.

Therefore, apart from wirelessly communicating over long distances, if you are able to accomplish the same basic task by utilizing an RS-232 transceiver attached to the SpeakUp followed by a standard serial cable attached to the PC, then you can almost certainly implement the design with a pair XBees instead.

mikroe did not give a clear answer to my question asked here.

I always been sufficiently underwhelmed by Mikroe's support and documentation.

With the proper Dynamic Time Warping (DTW) algorithm, you maybe able to implement your own SpeakUp with a VS1053 and a PIC32.

There are several Open Source implementations of the DTW available:

Dynamic Time Warping Algorithm

You should be able to port an Open Source version of the algorithm to many of the higher performance microcontrollers.

BigDog

 

[milan.rajik]

PIC32 is better than STM32 ?

 

[bigdogguru]

As in every case the best microcontroller is the best at the required task, best price, best familiarity and best comfort level.

PIC32 is a MIPS architecture, while the STM32 is ARM Cortex Architecture.

There is certainly nothing wrong with the STM32F4 series of microcontrollers, they are high performance of the ARM Cortex-M4 series and can operate at relatively high clock rates.


BigDog

 

[milan.rajik]

Ok. I will try to implement the DWT for PIC32 as I am familiar with PIC devices. It will be easier to write PIC32 code than learning ARM Cortex programming. Can I buy Arduino Due which has ARM Cortex processor in order to learn ARM Cortex processor programming ?

 

[bigdogguru]

Actually, you might want to consider STM's STM32 Discovery Kits development boards, they are well made, feature onboard SWD/JTAG programmer/debugger, often include several peripherals and prices range from $8 to $25 which makes them hard to beat.

STM32 MCU Discovery Kits

STM32F4 Discovery

Mouser - STM32F4 Discovery $14.88

The STM32F4 Discovery includes a MEMS microphone, Audio DAC and MEMS 3-axis accelerometer for less than $15 USD.

The STM32 Discovery Kits onboard SWD/JTAG programmer/debugger are fully compatible with the KEIL MDK-ARM compiler suite, as well as many other ARM compiler suites.

BigDog

 

[milan.rajik]

This is the SpeakUp and XBee Remote Control Board I have designed in eagle. Is this ok ? Should I make any modifications ? There is one CR2032 holder, one SPDT slide switch, One XBee socket, one mikroBus socket and another 2 X 8 pin headers. These 2 X 8 pin headers and mikroBus socket are for mikroe SpeakUp.