[RE Mote] Power Management on rev. B
RE-Mote in revision B has a different functionality than older versions. This section describes the functionality, commands and procedure specs of the power management on rev.B. The main goal was place a power supply microcontroller to manage multiple options from battery charger and add additional control enhacements. The duty cycle when system is off has controlled better, and we can get more information of that.
With all, we can added these basic characteristics:
- PIC16F1509 as main power supply microcontroller.
- I2C communication commands.
- Low power that turns off the system (by command).
- Get information about what still doing the battery charger.
- 200 bytes of additional user data.
- Interface more easely than last versions.
To communicate with power management module is through I2C. The address is 0x7F (support 100 kpbs at maximum). Drivers of power suplpy is uploaded in repo.
The next section analyses the commands one by one, explaining all options of that.
Next commands will be avaliable on contiki drivers
| Name | Register Number | Bits num | Read/Write |
|---|---|---|---|
| - Power Enable | 0x22 | 8 bits | R/W |
| - Current Charge Limit | 0x23 | 8 bits | R/W |
| - Charge Enable | 0x24 | 8 bits | R/W |
| - System Enable Input | 0x25 | 8 bits | R/W |
| - Config External Reference | 0x26 | 8 bits | R/W |
| - Hard Sleep Configuration | 0x27 | 8 bits | R/W |
| - Soft Sleep Configuration | 0x28 | 8 bits | R/W |
| - Secure Soft Time | 0x29 | 32 bits | R/W |
| - Get Voltage | 0x2A | 16 Bits | R |
| - Get Firmware Version | 0x2B | 8 Bits | R/W |
| - Get Number Cycles | 0x2C | 32 Bits | R/W* |
| - Data Custom Bytes | [0x32:0xFA]* | 8 Bits | R/W |
Register bits (address 0x22):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Enable bit |
This command cuts the general battery voltage to all system. Enabling this writting a "1" in this register means that these parts will not been powered:
- CC2538
- CC1200
- Power charger
- SD
Register bits (address 0x23):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Major bit | Minor bit |
| In this register, only the two LSB bits is allowed. | |||||||||
| This register describes the current limit to charge the battery. |
| Value | Description |
|---|---|
| 0 | 100mA |
| 1 | 500mA |
| 2 | By External Resistor |
| 3 | Stand By current |
Register bits (address 0x24):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Enable bit |
| One special option on power management is to stop the option to charge the battery. When this register is disabled (by 0), automatically stops the charge mode. This can be useful to get more control in battery charge, and it can be disabled if no battery is present on system. |
Register bits (address 0x25):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Enable bit |
| Write 1 to connect the battery to the system output. Charging is also disabled. |
Register bits (address 0x26):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Enable bit |
This register is related with the acquisition of battery voltage. Writting "1" means that the acquisition will be from external circuitery placed around power supply controller. Writting "0" is a microcontroller internal acquisition. There have no differences in fact, << make tests on two options >>.
Register bits (address 0x27):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Enable bit |
Hard sleep is used with RTC. Enabling this method, the PM will wait until an event of RTC is made.
- it can be used with SOFT_TIME register if we want to get a security methor to start-up if the RTCC fails. But, it consumes more power (Because the microcontroller will be checking this continually).
- it needs a shutdown_now command
Register bits (address 0x28):
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | Enable bit |
Writing "1" in this, cause a shut down in all system. This needs a previous "Secure Soft Time".
Register bits (address 0x29):
This register is the time Out expiration for Hard or Soft sleep. Any value highter than 0 placed here will count at sleep process. This is a 32-bit register.
Register bits (address 0x2a):
When we read this register, we will obtain the current voltage of the battery. The battery voltage is obtained by the same read command, and it could need a little time. The format of output is a uint16_t /100. Example: 338 --> 3,38 Volts
Register bits (address 0x2b): Get the firmware version. If is 15, we need to divide by 10 (1.5).
Register bits (address 0x2c) Number cycles have been placed as the number of sleeps taken. This could be useful if we use the external RTC (as hard sleep mode) and we will not fix the same date at init. Then, any star-up after 0 will not write the initial date config. Writing any value in this register cause to reset to 0.
Register bits: Starting accessible address: 0x32 Final accessible address: 0xFA
This 200 bytes space have been left free by user custom actions. User can save and load data temporally (is not flash) until the device will not powered.
Fill examples:
Firstly of our implementation, we need to ensure that we have the needed prequisites.
err = pm_set_timeout(2);
if (err == PM_SUCCESS) {
printf("pm_set_timeout: %d, pm_get_timeout: %ld\n",
PM_SOFT_SHTDN_1_3_SEC,
(uint32_t)pm_get_timeout());
// We need to write when can enter into soft sleep
err = pm_write_byte(PM_SOFT_SLEEP_CONFIG, PM_ENABLE);
if (err == PM_SUCCESS) {
printf("Readed: %u\n ", pm_read_byte(PM_SOFT_SLEEP_CONFIG));
}
} else {
printf("%s error\n", print_pm(PM_SOFT_TIME));
}
break;
As prior code, the first of our test, place in our Makefile the definition of "DATE" extracted from system. This is a code for a Linux, Mac OS should be similar:
CFLAGS = -DDATE="\"`date +"%02u %02d %02m %02y %02H %02M %02S"`\""
Also, we need to add the libraries on our code file:
#include "power-mgmt.h"
#include "rtcc.h"
This is an example test code function to set a Hard sleep period. The definition of PM_TEST_WITH_SOFT_SECURITY submit a soft timer in low power management as timeout. This code it could be placed inside any thread with:
/* Local defines */
#define TEST_ALARM_MINUTE 16
/* Hard Sleep: RTC Configuration */
printf("RE-Mote RTCC+HARD SHUTDOWN test, system date: %s\n", DATE);
if(strcmp("Unknown", DATE) == 0) {
printf("Fail: could not retrieve date from system\n");
PROCESS_EXIT();
}
/* Configure RTC and return structure with all parameters */
rtcc_init();
if (pm_get_num_cycles() == 0) {
/* Configure the RTC with the current values */
simple_td->weekdays = (uint8_t)strtol(DATE, &next, 10);
simple_td->day = (uint8_t)strtol(next, &next, 10);
simple_td->months = (uint8_t)strtol(next, &next, 10);
simple_td->years = (uint8_t)strtol(next, &next, 10);
simple_td->hours = (uint8_t)strtol(next, &next, 10);
simple_td->minutes = (uint8_t)strtol(next, &next, 10);
simple_td->seconds = (uint8_t)strtol(next, NULL, 10);
simple_td->miliseconds = 0;
simple_td->mode = RTCC_24H_MODE;
simple_td->century = RTCC_CENTURY_20XX;
if(rtcc_set_time_date(simple_td) == AB08_ERROR) {
printf("Fail: Time and date not configured\n");
}
printf("Wait a bit\n");
etimer_set(&et, (CLOCK_SECOND * 2));
PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));
}
if(rtcc_get_time_date(simple_td) == AB08_ERROR) {
printf("Fail: Couldn't read time and date\n");
PROCESS_EXIT();
}
printf("Configured time: ");
rtcc_print(RTCC_PRINT_DATE_DEC);
/* Configure the RTCC to trigger an alarm every TEST_ALARM_SECOND tick */
printf("Setting an alarm to tick at %u minutes\n", TEST_ALARM_MINUTE);
simple_td->minutes = TEST_ALARM_MINUTE;
if(rtcc_set_alarm_time_date(simple_td, RTCC_ALARM_ON,
RTCC_REPEAT_HOUR,
RTCC_EVENT_RTCC_WITH_EXT_SYSTEM) == AB08_ERROR) {
printf("Fail: couldn't set the alarm\n");
PROCESS_EXIT();
}
printf("Alarm set to match: ");
rtcc_print(RTCC_PRINT_ALARM_DEC);
/* Config PIC to get the event from the RTCC to shutdown the system */
#ifdef PM_TEST_WITH_SOFT_SECURITY
err = pm_set_timeout(2);
if (err == PM_SUCCESS) {
printf("pm_set_timeout: %d, pm_get_timeout: %ld\n",
PM_SOFT_SHTDN_1_3_SEC,
(uint32_t)pm_get_timeout());
}
#endif
err = pm_write_byte(PM_HARD_SLEEP_CONFIG, PM_ENABLE);
if (err == PM_SUCCESS) {
printf("Readed: %u\n ", pm_read_byte(PM_HARD_SLEEP_CONFIG));
}
err = pm_shutdown_now(PM_HARD_SLEEP_CONFIG);
if (err == PM_SUCCESS) {
printf("Theorically never reaches here: %u\n ", pm_read_byte(PM_HARD_SLEEP_CONFIG));
}
With this code in your application, the system will be shutdown preiodically each 1,3 seconds when arrives at minute defined by TEST_ALARM_MINUTE.
Add image and capture of the cycles:
Add power supply data: