NOTE: this firmware has been developed on board v1.2 therefore if you are using an early version and you notice something wrong don’t esitate to open an issue or a pull request. thank you.
- 100% free software. This was the main reason to start the project since I would a fully open source and future proof platform and the N7DCC’s mcu firmware is only available in binary form.
- use a by-directional ASYNC protocol between MCU and FPGA that can send ANY command at ANY time (probably we can implement a remote update of the MCU)
- each radio’s status is displayed on the screen; for example when you attach the power you see the STANBY screen or when you change the power amplifier status you get a message with the actual value.
- every configuration parameter is stored on the FPGA eeprom and not half on the MCU and half on the FPGA.
- full status on the bootloader screen
- amplifier values can be modified from the programmer (no mic needed)
- code comments everywhere
- free available PIC compiler (maybe move to SDCC)
- when you flash this firmware over N7DDC you need to re-calibrate the PD85004s resistor since the RA2 voltage is different.
| function | description | availability |
|---|---|---|
| radio power | the MCU manage the ON/OFF of the radio. You can power on/off with power button or MIC FST button | any time |
| display | manage the SSD1306 display printing the radio’s status (standby, bootloader, ready, PTT, ecc.) and the parameters | any time |
| fpga | an ASYNC UART channel between MCU and FPGA permits to exchange status and parameters (like, IP, version, slot) | any time |
| 1W power amplifier | manage the line that enable/disable the 1W power amplifier; configured by FPGA or a long press of MIC DOWN button (flip) | any time except transmitting |
| audio amplifier | manage the line that enable/disable the audio amplifier; configured by FPGA or a long press of MIC UP button (flip) | any time except transmitting |
| auto power on | you can power the radio the the power source is enable therefore without touching any button; good for remote operation | only at bootloader |
| change slot | permits to change the slot to boot with a short press of MIC DOWN or MIC UP | only at bootloader |
All configurations can be seen on the screen at bootloader and changed with the MIC or the programmer.
| PIN | description |
|---|---|
| RA0 | not connected |
| RA1 | not connected |
| RA2 | 1W Power Amplifier 1 = ON; 0 = OFF (enabled only during PTT) |
| RA3 | MIC FST long press power on the radio (like power on button) |
| RA4 | not connected |
| RA5 | MCLR used for programming reset |
| RA6 | Audio Amplifier 1 = OFF; 0 = ON |
| RA7 | MIC UP (pull-up) –> NO Interrupt on Change available |
| RB0 | power on button (pull-up) pressed when 0 |
| RB1 | i2c SDA display (pull-up) |
| RB2 | TPS62140 enable line (board 5V) 1 = ON; 0 = OFF |
| RB3 | MIC DOWN (pull-up) |
| RB4 | i2c SCL display (pull-up) |
| RB5 | not used - connected to FPGA J22 |
| RB6 | UART TX to FPGA L22 and CLK programmer (pull-up only when radio board is on) |
| RB7 | UART RX to FPGA L21 and DAT programmer (pull-up only when radio board is on) |
The protocol uses an ASYNC UART (pins RB6 and RB7) with the following parameters: 19200-8N1. The message exchange is half-duplex. The first byte sent is always a command. The next bytes are optional and depends on the command. An “FPGA ERROR” is shown in the display if the STAGE is not received. Each command that require an ACK must acknowledged before sending another command; in an another way, no multiple commands requiring ACK could be sent at the same time.
X X X X X X X X | | | | | | | | | | | | + + + + --> 4 bits for optional parameters | | | | + + + +--> 4 bits that indicate the command
| HEX | command | direction | stage | require ACK | next bytes | parameters | description |
|---|---|---|---|---|---|---|---|
| 0x00 | reserved | none | reserved command | ||||
| 0x1X | ACK | both | any | no | no | 0x? is the command to acknowledge | acknowledge command |
| 0x2X | STAGE | fpga to MCU | any | no | no | 0x0 = reserved | fpga inform the MCU in which state it is |
| 0x1 = booting | |||||||
| 0x2 = bootloader | |||||||
| 0x3 = radio | |||||||
| 0x4 = PTT | |||||||
| 0x5 = CRC error | |||||||
| 0x3X | VERSION | both | bootloader/radio | no | yes, 8 bytes | 0x0 = reserved | send the software version |
| 0x1 = MCU (not implemented) | |||||||
| 0x2 = bootloader | |||||||
| 0x3 = radio | |||||||
| 0x40 | IP | fpga to MCU | bootloader/radio | no | yes, 16 bytes | no | send the IP address to MCU |
| 0x5X | STATUS | both | bootloader | no | no | see below | send the status (see below) |
| 0x6X | POWER ON | both | bootloader | no | no | 0x0 = request data | mcu power on the radio just after the power connector is connected |
| 0x1 = enabled | |||||||
| 0x2 = disabled | |||||||
| 0x70 | SWR | fpga to MCU | PTT | no | yes, 2 bytes | no | send the SWR value to MCU to display it during PTT |
the optional parameters of the STATUS command have the following values
| bit | value | description |
|---|---|---|
| 3:2 | 00 | request the status |
| 01 | slot1 | |
| 10 | slot2 | |
| 11 | slot3 | |
| 1 | 0 | 1W power amplifier disabled |
| 1 | 1W power amplifier enabled | |
| 0 | 0 | audio amplifier disabled |
| 1 | audio amplifier enabled |
To build the software you only need two software:
- Microchip MPLAB XC8 available for Windows, macOS and Linux
- make (Posix compliant should be enough like, GNU make or BSD make)
If you have installed correctly the software above and xc8 is available in you shell you only need to run one command:
makeAt the end, you can see the “Memory Summary” and the firmware will be available at dist/default/production/mcu.production.hex
You can also use MPLAB X IDE if you would like to use an integrated environment to build and flash the firmware.
There are many in-circuit programmer in the market that you can select to flash the .hex the only requirements is to use ones that support low voltage programming. This is very important otherwise you can damage the FPGA (see the 4.5V zener in the layout). I used the following:
- PICkit™ 3 In-Circuit Debugger
- a-p-prog for arduino (remember to use delay
-s 1700)
Just pay attention on which device powers the MCU and if something fails double check the wire connections.
Copyright (C) 2020 Davide Gerhard IV3CVE This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.